GMC S15 Jimmy

1997 GMC S15 Jimmy Fuel System   

on acceleration around 1500 rpm and above engine cuts out rpm gage bounces and runs rough, replaced timing chain and gears, replaced, ignition coil wire/ plugs/ wires/dist. cap and bug. used dist. was installed, replaced fuel filter, tested IC module and coil, tested pcm on another vehicle no problems with IC module, coil or pcm. Has 60 psi fuel pressure, removed exhaust problem is still there.

Any check engine light while the engine is running?

Have you check the TPS- throttle position sensor. What about the map or maf sensor?

If you have CPI fuel injection, these are very problematic. Sometimes a professional cleaning helps.

1996 GMC S15 Jimmy Drive Train / Driveline   

will not switch from 4 wheel high to 2 wheel drive or 4 low... My cervice engine soon light has been on for a month or so..

Hello,

The first thing you need to do is have the diagnostics codes scanned. When the service engine soon light turns on a code or codes are stored in the PCM (computer). While complete diagnostics are expensive at the dealer, you can visit (Autozone, Parts America, and some other chain parts stores) and they will access the codes at no charge. Let me know which alphanumeric codes they find: Ex- P0300, P401, etc.

Thanks for responding so soon! Autozone's diagnostic was a P1870.

Okay, this is a vague code for transmission slippage. I hope you don't have state emissions inspection that require the check engine light to be off, if you choose not to fix the problem. While it is usually good to fix any problem that causes the check engine light to turn on, the p1870 code sets to easily. It will warn of transmission slippage when the amount is so small it may not be noticeable.

Is your 4wd actually stuck in 4 high (the wheels or front driveshaft turn), or the light indicates 4wd? Also which engine do you have?

It's actually stuck in 4wh high.. 4 high light is on.. The engine is a 6 cylander. I'll have to get back to you on the actual engine type..

ok the engine is 4.3 liter.. I just replaced the switch in the dash.. Still won't swith to 2 wheel.

Listen to see if you can hear the shift motor (called an 'encoder' motor) engage (or try to) when you push the shift button.

ok--If you're speaking of the buttons on the dash, it does make a clicking sound..

Okay, now check the shift motor on the transfer case and see if the cable to the front axle actuator is moving. Check these out carefully. Also check the vacuum lines, etc under hood, make sure there is no problem here.

ok

1996 GMC S15 Jimmy Engine   

About a month ago our Jimmy was running fine - we came out to start it up and it died. It would turn over but would not start. We had it towed home and I checked the fuel line pressure (15 psi). Replaced the filter and this helped a litte but no where near the 60 psi we needed. Replaced the fuel pump and the fuel pressure regulator. This got us to 50 psi- still not enough so I bit the bullet and bought a AC Delco conversion kit to change from CSFI TO CMFI. Now I am getting almost 70 psi from the pump and at least60-62 psi when running at 2000 rpm. Now it was starting w/o a problem and runing o.k. but a little rough and would stall after about 10 minutes at idle. But, there was a lack of power. On thke road the best I could do was 40 mph with the pedal to the floor. I got a DTC of P0118 so I replaced the ECT sensor and that cleared up the DTC code but stil no power. I cleaned the IAC valve and reset the pintel to 28 mm. The car finally had some power back, I could do 80 mph. That was short lived road trip and as the miles passed the speed dropped. At the end of a 25 mile trip I could only do 40 mph and had just enough power to climb a small incline.What do you suggest? Why the slow decline in power while I still have 60 psi fuel pressure?

Hi, Have you considered the exhaust may be restricted? I'm wondering if your engine just can't breathe? Could be a catalytic converter stopping up.

Roger

Is there any way to test the converter to see if it is the problem?

Would the oxygen sensors need to be replaced also?

With severe restriction the exhaust will hiss at the tail pipe on hard acceleration.

I have had success disconnecting the exhaust header pipe, tolerating the noise, and driving the vehicle to note the change in performance.

A local muffler shop may be able to help test the converter.

I don't think the oxygen sensors will need replaced. I do expect that O2 sensor codes will set during testing. Those codes can be cleared when testing and repairs are completed.

Roger

The more I thought about the suggestion that the cataytic converter might be the cause the more it made sense. The Jimmy runs fine in the morning and on short trips, but the greater the continous run time / distance the greater the loss of power. I just shelled out $200+ for a new Walker catalytic converter, plus I am replacing the two O2 sensors. The parts should be here in 4-5 days and I'll let you know what happens.

I'm very interested in the results! Consider NOT replacing the O2 sensors until a road test with the new converter has been done. You may be fine and save some money.

Roger

O.K.,I'll replace just the converter and run the same route (approx 30 miles w/ varied terrain and speeds) I ran when the problem emerged.

I'll look to hear from you!

Roger

Catalytic converter is scheduled to be delivered on 10/09/07.I'll contact you on 10/10/07

Haven't heard from you since Oct 3rd. Please update so I can try to keep up.

Thanks,

Roger

Sorry, I was out of town for a few days.

The converter seems to have been the problem.I replaced the catalytic converter and, as a precaution, I replaced the 02 sensors located prior to the converter and after the converter. These had never been replacted in the life of the vehicle (135k miles)

I disovered a 2nd heated 02 sensor prior to the converter. What is reason for two 02 sensors pre converter? One sensor for each engine bank?

Thanks for helpng me sovle the problem. I never would have guessed the problem was back pressure from a clogged converter.
The Jimmy now cuises a 75 mph w/o any loss of power and accelertion is like a brand new vehcile.

Man, I love a happy ending! Please click on OK to finish up to close the question.

I thank you,

Roger

1995 GMC S15 Jimmy Heating / Cooling System   

The heater/ac blower works on high only. Blows hot and cold. The air flow blend works fine- dash, floor, defrost, etc

Hi,
Couple posibilities :
a) heater motor relay
c) heater motor blower resistor
Regards,
Anthony

I CHECKED the 2 heater/ac relays mounted on the firewall and they are ok . Is there another relay? I assume the resitor is on the blower motor

2 relay.
check yhe heater motor resistor close to blower motor.it is rectangular.
regards,
anthony

resitor bad thanks

ok
regards,
anthony

1994 GMC S15 Jimmy Electrical / Lighting Systems Malfunction Happens always 

while tightening up the accessory power outlet last weekend I blew the fuse. I replaced that fuse and got the outlet to work, now I realize that my turn indicators are not working (neither left nor right). All the fuses are good and there is power to the blinking unit in the fuse block. I have a little chime unit wired into the blinking unit (for several years)and it chimes, but the turn signals don't light up and neither do the indicator lights on the dash. The emergency flashers do work (both lights and dash indicator)

Hi,
Sounds like your flasher died, a new one is about $5. Also turn on the hazards and make sure all the external bulbs are lighting, because a bad bulb can cause the flasher to not flash. This sounds like something unrelated to the original fuse problem.
Dale

1993 GMC S15 Jimmy Engine   

I am not quite sure how to catagorize this question. About two or three years ago I had my oil pump replaced on my 1993 GMC Jimmy S-15, and less than a year later had the lower intake manifold and a few other things replaced. Now my oil pressure is crap again. It reads at almost nothing, and when I stop it dips low enough that it trips the "check gagues" light. Thinking there is no possible way the oil pump is bad already I bought an oil pressure sensor switch today. I went to replace it and every mechanic, dealership, and parts store (including the back of the box of the part and my Haynes Manual) say that all Jimmys 1991 and newer have standard three blade sensors. For some reason mine has a single blade in there. No one can seem to figure this out, so I am giving this a shot. ANY info you have would be a help. Thanks.
Karl Otto

Could this be part of the problem with my oil pressure??

Hello Karl,
Where is the oil pressure sending unit located on your engine block? One wire-or-three wires won't likely be the cure. Get and install a cheap guage at Wal-Mart and see what the pressure really is. You may have worn bearings for the cam or crankshaft allowing oil to escape over the edge of the bearing instead of being pumped through the oil passages. A 'leak' as I've described outruns the oil pump as it tries to keep up.

Your thoughts?,

Roger

The bearings were replaced at the same time as the manifold were, so I would HOPE that wouldn't be the problem. As you are looking at the engine from the front of the car, the unit is located on the right hand side of the engine block, below the valve covers and just below the two ports for sparks plugs four and six. Any other suggestions? Wal-Mart sells the item I need to check the oil pressure myself instead of paying a mechanic $55 to do it? Thanks.
Karl

Now that I think about it, I should probably start at the beginning. When I was out to sea, two weeks before I came home, my wife was driving home, and just as she got there the engine started to overheat. The next day she got it over to Pep Boys (a mistake unbeknownst to us at the time since that particular one has a bad reputation) to have them look at it. They told her that the lower intake manifold had a hole rust through it (the mechanic seemed to be in shock that this actually happened to that particular piece of the engine). She got a great deal on a used one at a junk yard that checked out fine with the mechanic. When they went to install it they found out that the spider valve assembly was missing out of it. The junk yard said someone must have stolen it out of there and gave her a generous discount on the part. They ordered a new assembly and installed the part. What they didn't do was clean the burnt up crumbled pieces of the old assembly out of the oil pan. As those cycled through our engine it did a nice amount of damage and our engine started to "tick". We took it to a mechanic highly recommended by my chief at the time, who said hopefully only the oil pump was damaged. I bought the part and was going to do it myself until I found out that you have to raise/remove the engine to do it. I took it to the recommended mechanic and he did it for me for a great price. He was the one that found the plastic bits from the old spider valve assembly in the oil pan. Unfortunatly that didn't solve the "ticking". He tore the engine down for us and replaced the bearings, lifters, etc (basically the whole lower half of the engine) When we got it back it sounded and ran wonderful. Around this time last year we had the radiator replaced (I was out to sea again) and when my wife got it back it was running pretty rough. When I got home I went to replace the spark plugs and discovered that whomever had worked on it had the wires for spark plugs number four and number six coming off the distributior were switched around. Correcting that got it running nice and smooth again. It has been in about the last eight months or so the oil pressure problem has started. I do know that when the mechanic replaced our oil pump he didn't replace the sensor switch. The engine does not "knock" or "tick" in the slightest way, that is partially why we are hoping to God that it is just a bad sensor and not something else major like it always seems to be for us. Hopefully that will help you out.

All right, Sir! You've covered alot of ground here. I would absolutely install a oil pressure gage in place of the sensor and see what the pressure is, in pounds/sq.in. If your vehicle has a gage now, this will prove its' accuracy and would be my first test were it possible for me to be there. If pressure is indeed low, the oil pan comes off next to see if the oil pump pick-up screen is full of debris. Then, the inspection of the bearings for wear and to be sure they are still in their correct fitted position. Especially the cam bearings. A cam bearing can slip position and you won't hear noises.

Your turn,

Roger

Thanks. Do you know any tricks to get the oil pan off without pulling the engine? Can you really get an oil pressure gage at Walmart?

The only way you could hope to get the oil pan off without pulling the engine would be to disconnect the motor mounts and see how much clearance you get by jacking the engine. It will be trial and error to see, with the tranny still bolted on, it can be frustrating.

The gage at WalMart I'm speaking about is an aftermarket gage intended to mount in the vehicle and take the place of a light on the dash. You've seen them...if you've ever been to a car show. I'd only hook it up for testing under the hood and not bother with a complete installation unless it is attractive enough you choose to mount it where the driver can see it.

Perhaps you can rent a pressure gage at a national auto chain store like Autozone or O'Reilly's...

Roger

Hi, How is this repair progressing??

Roger

1993 GMC S15 Jimmy Chassis / Suspension & Steering Vibration When driving 

I have a 93 GMC Jimmy 4 door 4x4. It has developed a horrific vibration over bumps on paved roads at speeds above 40 mph. The vibration is felt throughout the vehicle (floor, seats, body), and I can actually see the hood shake. But the vibration is not really felt in the steering wheel.
Since the vibration has developed I have replaced the shocks, ball joints, and idler arm. The tie rods and pitman arm have checked out ok. But the vibrations continue and seem to be slowly getting worse. I have owned the vehicle since 1996. I have put over 250,000 miles on it and never experienced this kind of problem. It rides good at highway speeds, and actually seems good on bumpy dirt roads. But, bumps on paved roads at speeds above 40 mph causes horrific vibrations/shaking throughout the vehicle. Could it be a bad motor or transmission mount? Or maybe bad leaf springs? Is there any way to check the leaf springs? Please help! I'd like to get another 250,000 miles out of the vehicle as it runs great but the ride is increasingly getting worse and feeling unsafe! thank you.

ujoint or carrier bearing on drive shaft

I will check the u-joints and let you know. My vehicle does not have the carrier bearing.

The u-joints check out ok. Any other suggestions?

You might check your rear axle bearings. Pick up the rear of the vehicle and see if you get any play up and down in the wheels.

Thanks again for your suggestions. Unfortunately, the rear axle bearings check out ok. Do you have any other suggestions? I know it's hard to make a diagnosis without actually seeing/driving the vehicle but your suggestions are appreciated and I hope you/we can figure it out.
Thanks again!

the only suggestion that i have is to check everything in the front end carefully. pick the front end up, preferably under the frame so the suspension hangs, and shake the wheels back and forth and up and down. check front wheel bearings also. after this, i don't know what else to check without being there to drive it.

1993 GMC S15 Jimmy Fuel System   

my truck starts good and runs then after awail it starts to stumble then you can shut it off for about 1/2 to 1 hour and then it dont want to start but you can give it a shot of eather and it will run but stumbles it has a new new fuel pump new fuel filter new air filter new coolant sensor

The coolant sensor would be the best bet (as long as you replaced the one that sends the signal to the ecu not the guage or fan one!
Might want to do a fuel pressure test and check the pressure regulator as it does sound like a fuel delivery problem.
Also, this time of year, I see more water in fuel problems.
Easy test.Take a small sample of the gas.
Get a plain brown pce of cardboard.Dump gas sample on cardboard.Gas will immediatly soak in.Water will bead on top.

i replaced the coolant sensor all ready
do you think it might be the tps sensor ?
or one other of the menny sensors ?

TPS sensor and others should not be tested without first scanning for codes.You might be able to test TPS with a Digital Volt/Ohm Meter.Cleaning out the throttle body with a good aerosol throttle body cleaner is always a good idea.

we are dealing with a 4.3 vortec it has a cpi on it
i tryed to clean it frist
i have chenged all that i listed before
this engin run really good when it is cold and then it starts to stumble like i said
then you go to start it after you have warmed it up
and thats when it dont want to start back up
it sure does have me scatching my head trying to figer it out

Sounds like the coolant temp sensor (you might have a new one that is faulty)or thewiring to it.Try to get it scanned while it is running/driving.

1992 GMC S15 Jimmy Ignition System Won't Start  

I need to rewire the distributor cap. Where's number one on the cap?

Copy and Paste the following link into your address bar:

http://autorepair.about.com/library/firing_orders/bl-gmc-firing-92.htm?terms=gmc+firing+order

If you have trouble copying and pasting the link, simply vist about.com and search for "gmc firing order" and you'll find it this way.

1991 GMC S15 Jimmy Electrical / Lighting Systems Malfunction When starting No pattern

How to R&R the starter.

Hi:
Disconnect the battery. Take the two starter bolts out from underneath. Disconnect the red wire going to the starter and all the fusible links. Then disconnect the small wire going to the solenoid. Happy new years. Les.

My main problem is getting the starter out after removing the bolts. Front drive line and flywheel housing prevent removing the starter.

Hi;
you need to remove the bottom dust cover. There should be 4 bolts to it, and two brackets coming from the engine. Thanks Les.

1990 GMC S15 Jimmy Electrical / Lighting Systems Malfunction Happens always Always

Check engine light doesn't work I was going to try to scan the codes to find if another possible problem could be solved that way but the bulb is good and still no check engine light.

You might have a few problems. The check engine light is triggered by items in the intake, throttle body (carb) and exhaust system. To read the codes without a code reader try the following... take a paperclip jumper the a and b pins on the black computer access block... should be located under the dash either on the left or right of the steering column... then turn the key to the on position and your check engine light should begin flashing.. count the flashes.. they all come in series of 2 digits .. there are no single digit codes.. and the codes all repeat 3 times.. here is the bad part.. if you dont get any codes your computer is failing and that might be what is causing your "other problems" good luck.. AL

1990 GMC S15 Jimmy Drive Train / Driveline Slipping When accelerating Always

I spun a rear main in m y 4.3 liter V6 with 3 speed auto with overdrive. I replaced the engine with a healthy one from a recycler. Everything seems fine, except the engine races when accelerating, with the speed and actual acceleration not keeping up with the engine rpms. Could this be lingage, torque converter, motion sensor?

Your owners manual (distick should also) will tell you what the manufacturer recommends. Using anything else is taking a chance.
Anything other than Dextron series raises the potential for problems.

Have you checked the transmission fluid level? Make sure the level is okay. If the filter hasn't been changed recently try a new filter and fluid change.

Also check troublecodes. The VSS (vehicle speed sensor or motion sensor) should set a code if it has a problem."

I will check fliud level. I topped it off when I
reinstalled engine/drivetrain. I ran ouy of Dextron2
my kid had some F type tranny fluid I used 2 to 3
quarts of that. I was told I could use F type in
GMC, but could only use F type in older Fords. Let
me know if I'm wrong please, rjh.

1988 GMC S15 Jimmy Chassis / Suspension & Steering   

I am replacing a Winshield Wiper Switch in my jimmy and i have no idea what to do. If someone can please explain to me i would really appreciate it. Thanks

Hello, Do you have the tools to disassemble the steering column?

The turn signal switch and ignition lock cylinder must be removed for access to the wiper switch.

Roger

1988 GMC S15 Jimmy Fuel System   

why it doesn't start and run on the idleing circuit.

If the problem is it will only run above idle (runs good above idle) but not run at idle-

Start by checking for vacuum leaks. Next check the idle speed motor.

Is the check engine light on at anytime while the engine is running?

Which engine do you have?

check engine light stays on. my engine is 2.5 4 cyl.
This is a list of what I have already done:But did not help: Changed Idle air control, Changed TPS,Changed Injector,Checked pressure on the feul line 11.lbs, new map sensor, new fuel filter, new ignition module. will not run at all.
i put gas down the throttle body and it will run on that gas.

Start by checking fuses, most notably the ECM fuses.

Also check to see if you have Key On reference voltage to the sensors (you can check at the TPS). Look for 5 volts with one lead of DC Voltmeter (multimeter)to sensor connector and the other lead to a known good ground.

Also, check for Key On positive voltage to the fuel injector. One wire should have 12 volts with the key on. The ECM (computer) provides the ground (pulse). Remember to use a known good ground.

Which is of the above is missing?

Note- We are assuming the injector is not pulsing and trying to pinpoint why.

checked the ecm fuseit is 10a, ecm bwas checked also
which was 10a and also was good .throttleposion was it is 10 amps instead of 5. it runs only if you put fuel in the motor.

The TPS will have 5 volts reference. Does the fuel injector have KEY ON 12 volts positive (with other test lead to a known good ground)?

The throttle sensor is 4.99 volts and the fuel injector is 11.7 volts. ( do you think it would be wise to buy a computer for the Truck ?)

First check for trouble codes and the wiring from the dist. module to make sure there is not a problem here. Thoroughly inspect the connnectors.

Let me know if you need instructions on checking trouble codes by grounding the A & B terminals of the diagnostic connector (under-dash).

If you do try a computer consider used, they should be plentiful and cheap.

I will go to the Junk yard tomorrow to get another computer. I've had the battery unhooked to many times so I lost memory.I will let you know the out come tomorrow.

Put another computer in and that didn't help. Next suggestion

Crank the engine over then check the trouble codes. Any codes present?

just code #12 after that no signals come through.

1987 GMC S15 Jimmy Electrical / Lighting Systems   

NO BREAK LIGHTS,bulbs all good hazard lites work turn signals work switch checks out ok there is power to the switch

If there is power at the brake light switch and power from it to the signal switch then it is the signal switch. Most of the turnsignal switch circuits work, but not all of them.

where is the switch located

1987 GMC S15 Jimmy Engine   

i recently replaced the engine in my 1987 s-15 jimmy 2wd, now it wont start... I got the engine at a junk yard, from a 4wd, i converted the oil filter cap, replaced the oil pump for a 2wd, and used my oil pan, swapped the distributer, and timing chain. When i compted the engine replacement, i cycled the key once or twice to get the fuel up, and then it started right up, but i let it go dead, becouse, while it was running i realized i left the o2 sensor out, but after it died that time, never would start back, i then replaced the plugs and the wires, still nothing... i ave yet to recheck the rotor poistion @tdc, this vehicle has been sitting for 4 or 5 months, with the gasoline thats in it, i think just wont burn... How can i get this thing to start and run?

What was wrong with the old engine, anything that could of plugged the catalytic converter???

Remove the O2 sensor and see if the engine will start again, if it does there is likely an exhaust restriction (plugged converter or colasped pipe).

Do you still hear the fuel pump prime when you initially turn the key on and during engine cranking?

What about spark, do you still have spark to the plugs?

The old engine had dissipated main bearing with slivers of metal in the pickup screen. When trying to start the new engine, it is turning over but it won't crank. There is a spark and the fuel pump is priming. I am able to see fuel coming out of the throttle body, it just wont crank.

At this point you should probably pull a few plugs and see if the engine is flooded. If so, the ring may need to be soaked in oil for several hours (to gain back compression). Holding the accelerator to the floor will also aid in starting a flooded engine.

If you have a compression gauge, check engine compression.

You may very well be right, you may have pumped some watery gas into the engine. While 4-5 months old is longer than recommended, the gas will still run the engine. You may have pumped the water that settled/accumulated into the engine though. Clean and dry the spark plugs, as necessary, then unplug the fuel injectors. Try to start the engine on a small dose of carburetor cleaner (this will be the only fuel the engine is getting) sprayed into the throttle body before cranking engine. Only a small amount, because if the timing is off the fire may spit back out the throttle body, etc.

1986 GMC S15 Jimmy Engine Hesitating When accelerating Always

Engine runs great at idle and when up to speed but has terrible hesitation on acceleration (engine dies sometimes). Vacuum hoses have been replaced, timing is good, local mechanics have been stumped, I found a service notice: 86T186 -SEP 86 -Engine - Stumbles or Hesitates on Turns, but can't find details for this.

They also checked the fuel pump pressure, and it was OK.

The tsb involves the fuel tank on 2.5/2.8l engines with throttle body injection (TBI). When fuel level is low the pump can suck air when fuel sloshes around. Only applies with about 1/8 tank of fuel or less.
Does the service bulletin apply?

No, I have a full tank in it now and the hesitation is very bad, even died today when I reaccelerated after coasting down a long hill. I also failed to mention they did replace the O2 sensor as well.

Which engine do you have?

2.8 Fuel Injected, AC, Automatic (with Overdrive)

"Was fuel pressure and volume confirmed?
Did they check injector spray pattern and injector resistance or current?
Were TPS and MAP sensor inputs to the ecm monitored?
Did they disconnect EGR valve and road test?

It is really tough to guess what they may have overlooked. I would assume they have eliminated the ignition system from breaking down.

I know they checked Fuel Pressure and Map codes, as for the rest I can't tell you. They have always done well on our newer vehicles, I just don't think the computer on this one is smart enough to tell them what to do.

I'm taking it to someone else later this week. I'll add your suggestions to my list of things to check out.