micktroup2

My 3.1 was had an intermitent starting problem, smells rich, stumbles. Now it won't start at all. Found the vacuum line from the fuel pressure regulator to the air pump is busted.
Could that be the problem?

Project 3.4 Camaro

I don't have an air pump, so your car might route the vac lines differently, but yeah, FPR not being connected to the vacuum line is a bad thing, on mine it connects to the TB though. In fact, I'm not 100% sure it should even go to the air pump at all, but idk much about them so I may be wrong, but my understanding of the air pump is that it pumps air into the exhaust manifold, so wouldn't make sense to hook up the FPR to that...the FPR needs to see intake vacuum. But wait for someone else to chime in.
Also check your timing, could also even be fuel pump possibly.

SmArT-V6-

if its the fuel pump, wouldnt it just not start AT all?

bl85c

iTrader: (2)

Not neccecarily. They don't always fail like a lightbulb. The fpr vac line shouldn't be connected to the smog pump. Are you certain that's how it's routed? The line needs to be hooked up properly, but this shouldn't cause a no start.

micktroup2

I believe it is supposed to route to the air management valve at the back of the airs pump. I found the remains of a vacuum line there so I put a new one in that attaches to a 't' that goes to the fpr and the throttle body.
The car started, but as soon as I gave it any gas it stumbled and died. Next up is to pull the top plenum (AGAIN) and check the resistance on the injectors. I have a feeling that is the other source of the trouble...

micktroup2

If you know where that vacuum line for the FPR is SUPPOSED to route to on the 3.1(if I have it wrong!!) please let me know. A diagram would be a great help. Actually, I will check the Autozone website...

micktroup2

There is an air management switch on the back of the AIRS pump, that the FMR commects to via a vacuum line. I reconnected that and it started, but again stumbled and died if I tried to feed it any more fuel. Next stop: the INJECTORS! Gotta see if any of them have gone sour...

89-bird

Check your TPS if it is bad or going bad you can have a problem like you have of not being able to give it gas and it will stumble and want to die or just bog down real bad .

micktroup2

Found it, I THINK!! I thought I would tear it down and pull the injectors and have them checked out. Found one with a broken lock ring that was leaking gas from the fuel rail- NICE! But the kicker was when I decided to swap to my polished Fiero valve covers (wait until you see the set up...). I have thermo tech boots on the plug wires to protect them from the exhaust heat. My mechanic assured me that he had checked all the obvious stuff...! Well, when I pulled the plug wires, one of the boots made a NICE crackling sound. I got it out of the thermo tech boot and it came out in a cloud of WHITE CHALK! It was so fried that the black carbon build up had turned WHITE from the heat! I continued to disassemble and, since I needed to Pull the EGR valve to get at the valve cover bolts I found that the stalk the EGR sits on was sloppy! Apparently, it had either been put on finger tight or not at all, or it had blown a gasket out. Either way, it had been spraying exhaust gases RIGHT AT THE PLUG WIRE. When I pulled all the plugs, I found at least 2 that had not been firing, so another plug wire was bad too.

Once I get the fuel injectors checked out, I will reassemble and tell you how it runs. So far, the damage is:

1) missing vacuum line from the FPR to the AMS- replaced.
2) Bad plug wires- ordering Taylor 8mm wires from Summit.
3) Possible faulty injectors- to be tested.
4) leaking fuel injector- clips and o-rings to be replaced.
5) Blown plenum gasket- replaced.
6) Blown EGR gasket- to be replaced.
7) Suspect spark plugs- being replaced.

Oh, also leaking valve cover gasket and FINALLY (AS IF! with 3rd Gens...) I found where the leak in my floor boards was coming from. A NICE hole in my firewall that some douch had filled in with BONDO and painted over.... SIGH.

Maverick H1L

iTrader: (8)

Might want to opt for an ignition coil there, too, and may want to save for a module as well in the future. Neither one likes having the high voltage for the spark plugs run straight to ground without the resistance of the plug gap and fuel mixture in the cylinders (ask how I know!).

micktroup2

Lovely! Is this the most damnable car in the world to keep on the road, or do we just end up knowing so much about them that we CAN keep a car running that should have been junked eons ago??

Maverick H1L

iTrader: (8)

Ummm... Both? It's a love-hate-loathe relationship for most of us.

micktroup2

Well, checked the injectors: 4 read around 12 ohms, 1 read 16 and one read 2!!! And one of them was a different type than all the rest! So now I have ordered a complete set of Bosch injectors from Injector Connection. I checked one website from an injector servicing company and GUESS WHAT INJECTOR THEY SAW FAIL THE MOST? That's right: the 2.8/3.1/3.4 type that we use. Another quality GM decision that one. I am surprised they have not gone out of business. Oh wait...

LongHaulRS

I wanted to check with you to see if you found what the problem was. It's wierd we had all most the same problem at about the same time. Mine happened all of a sudden. Car was runnning fine when I pulled up to a stop sign, when I went to pull a way the car stumbled and died. It would have a hard time idling it would run very rich so I had to feather the gas just to keep it running, but it was running so rich that if I hit to fast it would stumble and die. When I gave the engine bay a once over to see if I could find the problem I found that the same exact vaccum line was disconnected. So I thought great fix the line and be one my way. The problem continued so I checked some of the basics once the tow truck got me home. I found that some of the wires were burnt due to a leaky EGR valve. So the EGR was replaced. I replaced the plugs since there were Ac Delco plugs ( I have all ways had problems with Ac Delco plugs dieing with in a couple of hundred miles). Also the crapy roads shook my MAP sensor lose. Tested The MAP and tightened it up. I had ignition mod. under the dist. cap tested it passed multipe tests.

At this point I still have same problem, but it seems to run a little stronger at this point. I have left my fuel presure tester hooked up so I could check the presure at different points. It was reading a little low at first, but I think that was due to a vaccum leak and the FPR couldn't controll the presure correctly. Once the all vac leaks were fixed it came up to 45PSI. Plus if the pump was bad it wouldn't running so rich witch has been verrified by an air fuel gauge and the shear amount of fuel left on the plugs. One wierd thing that I noticed is that if I disconnect the vac line that is on the same tee as the brake booster the idle jumps up and smoths out with no need to feather gas to keep it runnning, but it is still running pretty rich just not as much. As soon as it is pluged in it runs like crap. Shouldn't be the other way around? I was suspecting the injectors, FPR, or maybe my coil, but the coil appeared to pass the test in the shop book.

Some times the idle will rhythmically up and done by about 50 - 100RPMs. WHen this happens the fuel presure drops to about 30PSI. but it stills runs rich. when the up down idle stops the presure goes back up to normal. This is why I suspect either the injectors or FPR, but I hate to just chuck new parts at it. So if you could let me know what you end up finding out it may help me out. what shoud the injector Ohm reading be?

Sorry for the long post, but it is a wierd and difficult problem to fix. I normally don't have this hard of a time getting this going. I have put 417,000 miles on so I have worked on it more then a few times and it has all ways been good car. I would hate to have to get rid of it over this.

Maverick H1L

iTrader: (8)

As above, check your fuel injectors. If your fuel pressure is that low, either you have a fuel leak or you have a faulty injector or more. I don't see why you have problems with factory spark plugs. The rest of us don't. As a rule, most people keep the stock plugs with the engine (GM uses Delcos, Chrysler uses Champions, Euros use Bosch, Japs use Densos). If you keep having problems with the plugs, I'd check elsewhere in the ignition and fuel systems, as there are a number of things (weak spark, leaking injector, leaking FPR, etc) that foul plugs faster than anything.

burton98626

Wow, you have done a lot of work on your car. Did it have a 2.8 in it from the start and did you make it into the 3.4? I have a 2.8 in one of my Fiero's that will not keep running, it starts with the cold start injector only, runs 3 seconds then quits. On top of the fuel rail there is a fuel pressure connection to relieve pressure, there is no pressure there, should there be?

Picking your brain
Mike