SciFi

Hello.

car has been sitting awhile (3 or 4 yrs) got it to a local shop who got into it and said no fuel pressure and the float is stuck (or something like that ) so had both those replaced..
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Now another problem . The way I understand it, its getting fuel to the top , and when the ECM grounds that tells the injector to to drop the fuel in...

So the shop says we need to try a new ECM this MIGHT fix the problem..

so new ECM in we getting fuel and power to injector but nothing happeing..

So there sending the new ac delco ECM back (saved me $250) but im stuck with a car I cant get running and local shop pretty much isnt set up to run down electrical problems.. (local muffler shop guy has always treated me good in the past)

So I've got roughly $800 in parts in labor as is (didnt charge me the 6 +hours he spent hunting down problems and for installing and removing the ecm)

My last option is the dealership at $99 a hour

So anyone come across anything like this in the past?

there is a VERY high chance there might be some rat damage , there was a nest found near the intake..

So i have to ask , are there any local guys in or around dayton ,ohio that someone could point me to.. Because the price the dealership is about to charge me seems like alot of cash right down the crapper when I could just hook up with someone who works on vette's..

I'd much rather drop my cash on local guy than the dealer..

Thanks
SciFi

:edit: Motor will run when you dump fuel straight into it, then dies when gas runs out..

Z51JEFF

I know if the ECM sees no oil pressure the car wont start,its been years since I worked on an early C4.Keep looking and you will find somebody to find the problEM.I would NOT take that car to the dealer.

SciFi

about a hour after I posted this I went to gas station to fill up my other car,

tow truck pulls up beside me and its a old buddie I haven't seen in few yrs..

we start talking and he hooks me up with a local guy that has done work for me in the past..

I call him up tell him whats going on and he thinks he knows whats wrong with it but cant be sure till he gets his hands on it..

he works at a dealer (20+yrs)and does side jobs for extra cash..

so one trip to the gas stations lands me a cheap tow to his place($50 vs. $90 and land a good local guy that charges $40hr vs. the $99hr)

I'll update on the outcome ..

would still like some advice to what others think might be the problem

Jrventure

I have a 1982 Crossfire, 32k original miles and has been driven very little for the past several years. I put it away for the winter and just replaced the battery. The car is cranking but no fuel coming out of the injectors. The fuses 20 Amp in battery box looks good and the two fuses underneath look good. What steps should I take before taking it to a shop for possible, fuel filter replacement, fuel pump etc..

Before spending a fortune?

Are there any cleaners?

Thank you

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rickraptor1980

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Did you ever find the problem ? I'm going thru the same issues

Cliff Harris

Not true for several reasons. One is that the oil pressure switch/sender is not connected to the ECM so the ECM has no way of knowing what the oil pressure is. The oil pressure switch is only a BACKUP for the fuel pump relay, which is operated by the ECM. The engine will run just fine with the oil pressure switch disconnected.

Tom400CFI

So long in fact, that you've forgotten (?) how they work. They car WILL indeed, start with no oil pressure.

Tom400CFI

Injectors have power w/key on. ECM grounds injector to fire it. How do you know the injectors aren't firing? Have you put a Noid light on it? Have you checked fuel pressure?

WHAT IS YOUR FUEL PRESSURE? That would be "Step #1" here.

Tom400CFI

Check your fuel pressure.

Just realized how old this thread is. Whoops!

1984Z51auto

For rickraptor1980: The advice you already have is correct. Try a noid light on the injectors to verify they are being commanded to fire and check your fuel pressure to the injectors. It should be about 13 PSI measured between the two injectors. It is a hassel to make up a gauge with the right fittings but that is the best place to take a reading. Be careful removing the fuel line between the injectors, it is usually stuck tight and will bend if not treated with lots of penetrating oil and care.

Tom400CFI

No. The best place for taking a reading is the place that is easiest to run the test and provides an accurate reading. That would be the rubber hose between the frame rail and the engine. The reading there will be no different that one taken from between the two injectors. No need to fab up special fittings etc.

1984Z51auto

You can take the reading as Tom states but, if anything is restricting flow between the hose and the pressure regulator in the last TBI... it may not be clear what or where it is. Any reading is however better than not knowing. The FSM recommends between the TBIs. You have to make up a "T" fitting either way. like this:

Fuel tank------T------TBIs---Return line or Fuel Tank----TBI---T----TBI---Return Line

Hook the gauge to the bottom of the T. Don't do this: Fuel tank---gauge

It will just tell you the max pressure the pump makes deadheaded.

Cliff Harris

How does that work? Since some of the fuel is being bypassed by the regulator back to the tank then won't that affect the pressure reading before the fuel gets to the injector with the regulator in it?

1984Z51auto

The regulator is in the last TBI and if everything is working right with no restrictions the pressure between the regulator and the pump will be constant at the regulated setting. This assumes no friction losses in the line. If the pump lacks capacity to meet demand, the pressure will be less than regulated when accelerating and if there is restriction in the line the pressure during acceleration will also drop. If the return line is blocked or restricted the whole system may show high pressure up to the pump deadhead pressure when there is minimum demand (idle) and abnormally high pressure at most other times.

Tom400CFI

That^ is exactly right.

No. It's a simply hydraulic system. Fuel pressure should be the same from pump to regulator. Only time that won't be true is with a badly clogged fuel filter.


EDIT: Maybe I should have clarified that by taking a reading, you would "T" into the line as 1984Z51Auto stated.

Cliff Harris

That part I don't have a problem with. What I'm wondering about is what the fuel pressure is AFTER the regulator, which seems like the important thing to measure.

I have seen two methods for measuring the pressure after the regulator:



...and this kludgey-looking setup:

Tom400CFI

Both those pics are showing location options to measure pressure BEFORE the regulator. The regulator is in the rear/driver's side TBI tower. Everything that is the first TBI tower, the connecting line (with that fitting in it) and the second tower, ....all that is essentially the "fuel rail". As in a TPI motor, that is all charged with feed line pressure. In fact, in that second/bottom picture, you can actually see the regulator and spring, as someone has cut open, or "window'ed" the FPR housing. In that pic, the rusty line is part of the "fuel rail", and the silver line is the return.

It doesn't really matter what your return line pressure is, as long as your main line pressure is where it needs to be. Return line pressure should be zero PSI (or what ever PSI is present due to friction of gas flowing in the return line....maybe ~1 PSI?)

.

1984Z51auto

I believe the issue here is the way the pressure regulator works. It restricts the fuel flow between its own location in the last TBI upstream to the pump. The regulated pressure side is between the pump and the regulator in the last TBI. The return line sees only the bleed off or excess that the spring loaded regulator valve lets pass down stream back to the tank.

Tom400CFI

That is correct. No different than in any other return style EFI system.

Cliff Harris

Apparently the way I thought it worked was backwards. I thought the fuel came in to the rear throttle body and the fuel pressure regulator fed regulated fuel pressure to the front throttle body.

So you're saying it's the other way around and the fuel comes in to the front throttle body and the rear throttle body bypasses the excess fuel and thereby regulates the fuel pressure for both throttle bodies.