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Discussion Starter #1
Hi, new member here and new to diesels, but learning quickly by reading posts.

I also posted the problem on the GM-Diesel forum,
and after several trial and errors I still have a stock '96 suburban that wont run.

I bought the burb in Aug 05. It had 170k back then. Currently it has 193k (and holding) until it's fixed.):h

Here's the problem:
Last Tuesday it gave me it's first issue. I was driving on the interstate for a couple of hours headded home and stopped for dinner. When I started it up and backed out, it ran really rough for 30 seconds or so and died. It will not restart and run. It will start and immediately die after 1/2 a second.

The Chevrolet dealership said it was the oil pressure switch and lift pump. I replaced both these parts via NAPA and it still immediately dies.

I loosened the fuel cap to relieve any pressure. It d/n fix problem.
I changed the fuel filter after cleaning out the bowl. It d/n fix problem.
I then hard wired the lift pump to bypass the relay and ensure fuel is reaching the IP. It d/n fix problem.

Someone mentioned the optical sensor. I'm clueless on how to check out this idea.
I have not read any codes at this point.

This morning I played with it for a few minutes and tried starting it again. I noticed it would run as long as I held the key in the start position. So I played with this position a little and once the engine fired I backed off the key ever so slightly until the starter disengaged.

Guess what - it kept running, but not very well. It was sputtering like it was running on 3 cylinders. I pushed on the "gas" pedal & absolutely NOTHING happened. I couldn't get it to REV up at all. It was running limplike for about 5 minutes while I tried poking around with different things. Then I had to go to work.

PMD going bad??? BTW, I ordered a Kennedy kit yesterday after reading several posts about the PMD going out. (My cruise hasn't worked for 2 months).
IP going bad??

Fuel relay gone bad??? But I hardwired the lift pump to bypass this (at least in my mind it bypassed the relay). How can I jump this to run mode?

Thank you for your help and ideas.
 

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Any codes?

It is either fuel, ignition, or internal IP problems.

Try starting it in limp mode by unplugging the optic sensor on top of the IP. If it will start with the optic unplugged but dies when you plug it back in, the optic sensor is toast.
 

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Hey Don. Glad you made it over here. Copy and paste the questions at this link to your post here and answer them as best as you can. It helps everybody get familiar with your rig and starts the search for your problem going in the right direction.... http://dieselplace.com/forum/showthread.php?t=42248
 

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Don check your PM I'm next door in Gautier I mite be able to lend you a hand

edit your signature line with truck info so we can better assist, read welcome note linked in my signature
 

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Discussion Starter #5
1.Lift pump test - pass​
2.Service Engine Light: off
3.Model year: 1996 Suburban 3/4 ton 2wd.
3a. Odometer reading: 193,000
3b. Miles on major engine components if been replaced. Nothing's been replaced that I know.
4.Do you have any engine codes? Don't know. Do I need a code reader?
5.If you do have engine codes - what are they?
6.Air Filter condition (visual check): Good
7.Fuel filter condition (freshly changed or condition unknown): Just replaced.
8.Condition of Battery terminal connections (cleaned and tightened): cleaned & tightened.
8A.Known condition and age of the batteries. New & excellent.
9.Upon cold start, does the radiator hose get hard quickly? Cannot check b/c it won't start.
10.Upon cold start, do you have excessive white smoke? No
11.Do you have excessive cranking time before the engine starts? No
12.Have you used the block heater, and does this effect engine starting? No
13.During hard acceleration, do you have excessive black smoke? No
14.Do you have any unusual exhaust smoke issues? No
15.Turbo check out - Don't know, but I think it is OK - great power & no black smoke.
16.Do you have an EGR on the engine? (An F or an S engine code) Don't know. But my VIN is: 3GNGC26F1TG101200 does that help any?
17.Indicate if you know if it’s a 2500 3/4 ton 2wd.
18.Indicate fuel that you are using: #2 Diesel
19.Are you using any fuel additives? If so, please list. Yes, but cannot remember the brand. It comes in white plastic container/ red letters & I buy it at the local truck stop.
20.Please indicate geographic region you are in: Coastal Alabama
21.Do you have any service history available that might pertain to the problem you are having? Nope. Just did a fresh oil change though.
22.Please indicate any modifications to the vehicle that might help us diagnose better. K&N air filter years ago.
23.Upon unscrewing the fuel cap, do you have a large vacuum formed in the tank? Maybe, I heard a vacuum sound but it did not sound to impressive.
 

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Does the SES icon appear on the dash when you turn the ign. key from off to on? if it does appear to light, then the bulb is good, if not, expect codes.
 

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I had the Exact same problem with mine a few months ago. It was the Fuel shut-off switch mounted on the intake manifold right behind the T-Stat housing. that will probably fix your problem.

 

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This morning I played with it for a few minutes and tried starting it again. I noticed it would run as long as I held the key in the start position. So I played with this position a little and once the engine fired I backed off the key ever so slightly until the starter disengaged.

Guess what - it kept running, but not very well.
I had an old GM dump truck that did the same thing. It was the ignition switch. In our trucks, not the key part but on the steering column iirc. You could check the fuel shut off as mentioned above by seeing when it is getting or not getting 12 v.
 

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Discussion Starter #9
I canceled the PMD I ordered & have a friend who has an extra. We're going to plug his in tonight as a test to see if that's the problem.

We'll look at the fuel shut off switch too. When should there be current at this switch? When running or when off?
 

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Well I went by and eyeballed this, threw me for a loop, thought for sure a driver would do the trick, tried his, no-joy, his new used but good spare still no joy, and finally my spare still no joy.

Fuses good, ignition good, relays good, lift pump good, scanner says shutdown solenoid problem, IP fault 1216, and cylinder imbalance all 8 cyls, not looking good says me, well check for power at shutdown solenoid.

What's this I say just before unplugging power connector, wobbly solenoid body, here wiggle this while I try to start it, sputter, start die, then finally a run then die. I think we got it, need a new shutdown solenoid then we will see what else we may see, but I'm guessing coil itself or power to coil at the coil is making intermittent contact.
 

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Discussion Starter #11
Yes, Tim stopped by my house in route to Home Depot and was a big help. He took me for a ride in his very fast '98 6.5TD truck. Awesome! My son & I had big smiles for the whole ride. Woohoo!

Tim discovered my wiggling fuel shut off valve. I held it steady while he cranked and it fired and ran for a few seconds. I suppose this is the culprit, but there may be more - hopefully not. I'll keep this thread updated as progress is made.

The dealership sells this part seperately from the IP. They called it a valve and not a switch or more precisely the Fuel Shut Off Solenoid Valve, PN 12561591 and sell it for $231.69.

Thanks for everyone's input and suggestions in helping figure this out.
 

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Don, I don't know how quick you need it but I think Heath or SSDiesel sell that for around $100 iirc. Someone help him out here. Am I remembering right?
 

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HAHA told you so!! Mine was wobbly too. My dealer wanted $200something for it and I got mine from SSdieselsupply.com for $90somthing.
 

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Discussion Starter #15
HAHA told you so!! Mine was wobbly too. My dealer wanted $200something for it and I got mine from SSdieselsupply.com for $90somthing.
Yup you were right!

So does this thing just unscrew from the IP? It looks like it has a bolt head on top of it.

Thanks, Don
 

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Discussion Starter #16
Here's a pic I got from the dealership showing the IP, PMD and Fuel Shut Off Solenoid Valve.

 

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It does unscrew. Mine was a pain to unplug/plug in b/c I have the dual t-stat housing. I had to recruit my little brother to do the plug b/c his hands are ssmaller. It might not be as dificult on your truck though.

Good luck!!
 

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i'd say :
1) OPS/LP
2) Ignition Switch {esp given reported result}
3) Shuttoff solenoid...or connections anywhere...be nice to know what's happening to voltage across that coil, but prolly need scope. In a coil, when the power is first connected, the current flow begins slowly, and builds up.
 

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Here's a tip for Ruling out ESO Solenoid problems, or avoiding them altogether.

Unscrew the solenoid from the pump and use 'squeeze to close' snapring pliers if you have them to remove the snap ring that holds the plunger in the body. Simply gut the solenoid and replace the hollow body back where it was and plug it back in. I have done and seen/heard this done before and it WILL NOT set any codes and if it was the problem, it won't be anymore.

However, if you have a wobbly solenoid its going to be pretty tricky to remove it and not break it, so you might see if you can find a spare first just to be on the safe side. Even if its a known bad one, it will work fine when its hollow.
 

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It's pretty far gone TDG, we located him a replacement today, so if to snaps off the rest of the way he will be good to go.
 
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