
Ask A Question - Help - Register - Login

1988 GMC Jimmy T15 4.3 Won't start. Gets spark, ...

Sent to Car Experts August 20, 2006 12:14 a.m.

1988 GMC Jimmy T15 4.3 Won't start. Gets spark, but no gas. But! if I pour a little gas into the Carb it will run as long as I keep the engine revved up. As soon as I let off the gas it stops and I have to prime it again. When not running but cranking their is no gas coming out of the injectors. Any ideas? It was running great until I came to a stop sign and it died and had to have it towed. Replaced the ECM and coil so far. Thanks for any suggestions.

Optional Information:
1988 GMC Jimmy S15 4.3

Already Tried:
new computer, new coil, checked all fuses,

Customer (name blocked for privacy)

Status: Closed Value: $10

Answer
August 20, 2006 12:34 a.m. (20 minutes and 35 seconds later)

REPLIED

You definately have a fuel delivery problem.Now that being said you can test this at the fuel pump relay.You will need a 12v test light to check this with.The fuel pump relay is located on the left inner fender panel.When you look at the wires the orange wire should be hot all the time and the pcm pump control wire is dark green/white tracer and should be hot when cranking.See what you have for power.Let me know your results.

mrrowland1 -- Auto Service Technician -- 100% Positive Feedback on 189 Car Accepts
Working Certified ASE Master /L1 (advanced engine pefromance) Technician

Reply to mrrowland1
Sent August 20, 2006 12:45 a.m. (10 minutes and 40 seconds later)

Yes, I forgot to mention I took the fuel line off the carb and turned the key on. The pump works but I don't know how much pressure it has. Shouldn't it pump at least a little gas into the injectors with any amount of pressure? The carb is bone dry.

Customer (name blocked for privacy)

Answer
August 20, 2006 1:01 a.m. (15 minutes and 43 seconds later)

REPLIED

The pump should put out,volume wise,1 pint in 30 seconds.If it can't the pump is worn out.Now you can also check for injector pulse with a test light.unhook 1 injector,hook the test light across the terminal,and have someone crank it over.should start blinking.

mrrowland1 -- Auto Service Technician -- 100% Positive Feedback on 189 Car Accepts
Working Certified ASE Master /L1 (advanced engine pefromance) Technician

Reply to mrrowland1
Sent August 20, 2006 9:25 a.m. (8 hours and 24 minutes later)

I will try that today, in the mean time I took off the "original" fuel filter. Need to go to town and get another plus line and a test light. Will get back to you afterwards. I have been fooling with this thing for a week and hopefully will get it running by tonight for work. Will be back soon.

Customer (name blocked for privacy)

Answer
August 20, 2006 9:26 a.m. (1 minute and 30 seconds later)

REPLIED

Ok,i'll be around today

mrrowland1 -- Auto Service Technician -- 100% Positive Feedback on 189 Car Accepts
Working Certified ASE Master /L1 (advanced engine pefromance) Technician

Reply to mrrowland1
Sent August 22, 2006 9:36 p.m. (2 days and 12 hours later)

I just installed the fuel filter. Needless to say I had a full tank of gas and laying on the ground getting drenched is no fun. I bought a fuel tester but didn't have the fittings to hook it up. In the meantime I had the ignition module tested while I was at Autozone and it was o.k. Its still the same....as long as I put gas in the carb it will run. Let off the gas and it quits. The injectors show 2.5 ohms. The test light shows 12 volts to each in the harness. When I put the testor across the wireharness connector how bright of a "blink" is there suppose to be? My tester has a light and is also audio. No sound, but and I'm not sure if its showing a really faint light or not.

Customer (name blocked for privacy)

Answer
August 22, 2006 11:18 p.m. (1 hour and 41 minutes later)

REPLIED

It should blink real bright while cranking.If you can have someone crank it over while you look at the injector signal.Should be short,bright flash.

mrrowland1 -- Auto Service Technician -- 100% Positive Feedback on 189 Car Accepts
Working Certified ASE Master /L1 (advanced engine pefromance) Technician

Reply to mrrowland1
Sent August 23, 2006 12:00 p.m. (12 hours and 42 minutes later)

o.k. I put 1 lead of the test light in each terminal on the injector terminal. And then the same with the other terminal. NO Flashing light. I measured resistance in each injector and they are each around 2.5 ohms.
Hope your not getting as sick of this car as I am.

Customer (name blocked for privacy)

Answer
August 23, 2006 3:36 p.m. (3 hours and 36 minutes later)

REPLIED

Alright,the ECM needs an rpm signal to pulse the injectors.Did you change the prom over from the old ECM? Now on this system,the module send an rpm signal to the ecm so the computer knows that you want this to start and run.Are you getting a good spark? I would have to say you may have a bad module. As we say garbage in,garbage out.Let me know if you have good spark.

mrrowland1 -- Auto Service Technician -- 100% Positive Feedback on 189 Car Accepts
Working Certified ASE Master /L1 (advanced engine pefromance) Technician

Reply to mrrowland1
Sent August 23, 2006 6:16 p.m. (2 hours and 39 minutes later)

I changed the prom over from the old ECM. Would it be fair to say I have a good spark if the engine runs when I pour a little gas in the carburetor? Or do I need to check the spark another way. All I have is a multimeter and a test light to check spark.

Customer (name blocked for privacy)

Answer
August 23, 2006 11:04 p.m. (4 hours and 48 minutes later)

REPLIED

No,i was at work when i e-mailed you.I forgot you said it would run with fuel dumped down the throttle body. Well,if no pulse,can only be 2 things.Open in the wiring or a defective ECM.The injectors recieve power from inj.fuse A in the interior fuse panel.the wiring goes straight from the injectors to the ECM.The specifications for your injectors is 1.3 ohms. Take you ohm meter and ohm the wires from the computer to the injectors.Pins #d14 and d16 (green and blue wires)at the computer.Should be close to zero.If that checks,replace the pcm.Have you checked all the fuses and fuseable links?

mrrowland1 -- Auto Service Technician -- 100% Positive Feedback on 189 Car Accepts
Working Certified ASE Master /L1 (advanced engine pefromance) Technician

Reply to mrrowland1
Sent August 24, 2006 1:19 p.m. (14 hours and 14 minutes later)

I checked all fuses and fuseable links. Before this all started A fuseable link off the alternator burn up. I soldered another section of wire into it. But, I have been driving it for a few weeks until this happened. I will check the wires you specified above and get back with you.

Customer (name blocked for privacy)

Answer
August 24, 2006 3:36 p.m. (2 hours and 17 minutes later)

REPLIED

Ok.I'll be online after work.

mrrowland1 -- Auto Service Technician -- 100% Positive Feedback on 189 Car Accepts
Working Certified ASE Master /L1 (advanced engine pefromance) Technician

Reply to mrrowland1
Sent August 25, 2006 12:54 p.m. (21 hours and 18 minutes later)

Well, I have been fooling with this thing for almost 2 weeks and I've finally had enough. I'm throwing in the towel. If I had started with you sooner I probably would have got it fixed by now. But, I didn't know about your web site. They came today and towed it to the garage before I lit a match on the gasoline leak to get rid of it forever. I thank you for your help, I know you could have got it running if I stayed with you. Send me a reply and I will click on accept so you can be paid. If I run into trouble again, you will be the 1st person I ask for help. Have a good day...........Bob

Customer (name blocked for privacy)

Answer
August 25, 2006 1:08 p.m. (13 minutes and 42 seconds later)

ACCEPTED

Anytime you need help just send me an e-mail.Have a great day!Images available only to Customers.

mrrowland1 -- Auto Service Technician -- 100% Positive Feedback on 189 Car Accepts
Working Certified ASE Master /L1 (advanced engine pefromance) Technician

Think you can answer this question?
Login or Become an Expert

Related Answers:

	DISCLAIMER: You acknowledge that any information you may obtain from individuals you contact through use of the Just Answer service comes from those individuals, not from Just Answer!, and that Just Answer is not in any way responsible for any of the information these third parties may supply. The site and services are provided "as is" with no warranty and no representations are made regarding the qualification of an Expert. Responses and comments on Just Answer! are for general information and are not intended to substitute for informed professional advice (such as medical, legal, investment or accounting) and do not establish a professional-client relationship. Just Answer! is not intended or designed to address EMERGENCY QUESTIONS which should be directed immediately by telephone or in-person to qualified professionals. Please carefully read the Terms of Service.

Just Answer! > Car Repair > Gmc Questions