ccorvetteracing

This has been a year of nothing but problems and my latest problem is my engine is flooded in my 1992 LT1 with 176,000 miles. I have been having fuel problems all summer. The sending unit wasn't working (I found out when I ran out of gas backing up my driveway and when I filled it up I put 19.5 gallons in it and the gauge said 1/2 tank) and I thought the pump was going out. So I took the unit out of the tank to check it out and to check to see if the tank was dirty. The tank was half full so I could only see the top half but it was spot less. The pump stainer was clean. So I tighten the sending unit screws a 1/4 turn and put the unit back in the tank (sending unit looks like it's working now). Then I thought maybe my filter is very dirty because of running it out of gas and pulling all of the crap at the bottom of the tank though. So I changed it about 50 miles ago. Now the last time I drove it was flooded on first start of the morning and took an hour to get started and I drove it to the picnic and it start fine for the drive home. Now today I go and start it I smell gas right away. It never even tried to start. I tried for a half hour. So I'm thinking a fuel injector is leaking. I believe I will need to replace the injectors. So what do you guys think and how do I diagnose this? Btw I replaced the plugs, wires, and coil 8000 miles ago. Any help would be great! Thank for reading all of this.

eatmydst1234

Pull the vacuum hose off the fuel pressure regulator. It's there any fuel in the vacuum hose? If so the fpr diaphragm ruptured and you need to replace the fpr. Fairly common problem.

floridamale

First thing I would do would be to pull the line off the FPR make sure there is no gas in the vac line a bad FPR can cause excess gas to be sucked into the plenum which then enters the cylinders and washes down the walls past the rings. This can give a very strong smell of gas

eatmydst1234 beat me to it

leesvet

YEp...

ALSO.........

2 things...

IF there is NO gas in the regulator vac line, then CHECK the OIL ! ASAP
These EFI systems can short the injectors so they stick WFO and POUR raw fuel into the cylinders...FLOODING. when you crank it, the liquid has no choice but to squeeze past the rings and enter the pan....filling the pan with gas and destroying the oil. Gas is a solvent...so it destroys the oils ability to lube anything.

IF the regulator checks out ok, then there is a short in the inj harness or sometimes a single injector will short internally and short the whole bank. That's harder to pin point but it can be done by pulling inj plugs 1 at a time until you find which is causing the problem.

Just beware....when an EFI engine floods....there is something seriously wrong. DO check the oil. I'd bet there is an extra few qts of something in there...

ccorvetteracing

Checked the fpr line and no fuel in it and didn't have a strong smell of fuel. Checked the oil level and that's fine. I checked the ohms of the injectors and 1,3,4,5,7,8 were 14.8 and 2 and 6 were 14.7. I checked the volts on the wiring harness side with the key in the ignition in the run position and they were 1.5-1.6.

desertmike1

Any or all the above... Now; in between trouble shooting sessions, and Especially when the car sets overnight, loosen the fuel cap just enough to prevent any fuel pressure build up inside of the fuel tank. This will help to prevent the pressure/syphon past a leaky??? and into your oil pan.

csthews

I guess I didn't read this right because it seems like you put 19.5 gallons of fuel in a 20 gallon tank and it was only half full. Can you clear that up for me, because if that is the case, you have more than a flooding issue.

ccorvetteracing

The gauge said half full when I only had and half gallon left. The gauge gets the fuel level information from the sending unit which is in the fuel tank which is working now.

leesvet

well, your ohms testing says the inj are electrically OK.
That does not mean they are ok mechanically...the nozzle and tips can leak down and bleed fuel.

The short (IF there is one) can be intermittent. The wire harness on these cars is crap. The insulation dry rots, cracks in the insulation and it cross shorts or grounds out to whatever is handy. I had to chop out the entire driver side harness and solder in new wire. The passenger side was perfect.....never figured out wtf or ?

As suggested, loosen the cap when you park. There is no easy way to bleed off the pressure once the rails are charged with fuel. You could unplug the pump and run the engine till it dies....but that's a hassle.

does it flood every time it sits? or just occasionally? random?

Might want to look at the TPS as well...the ECM looks at TPS position to see where it is to regulate fuel at start up and prevent flooding. IIRC it shuts off fuel at WOT with no run conditions.

If you have a fuel test gauge, install it, run the engine and shut down. See how long the pressure stays in the rails. If it falls to near nothing after only a couple hrs...that indicates fuel bleed off or leak down. Fast drop off (seconds or a minute) indicates the pump check valve is faulty.

floridamale

Another place to check is the charcoal canister line that runs from the tank to the front of car on driver’s side that can go bad and cause a gas smell also

ccorvetteracing

It flooded the last time I went to go start it (last Sunday) and now today

ccorvetteracing

September 15 Sunday is what I meant

C409

..... Do you have spark from the coil ? ............

383vett

Pull the plugs. Are they wet?

csthews

Get a test gage (from just about any parts store for around $20). You don't have to crank the car, just turn the key to on position and the fuel pump will run for a few seconds and pressure up the fuel rail. Just be careful hooking up the gage to prevent spraying fuel all over the place (assuming the rail is under pressure).

ccorvetteracing

I got a fuel pressure gauge and tested it read 40 psi then I checked it every hour. After the first hour it was down to 35 psi. At the 2nd hour it read 30psi. Hour 3 read 27psi and hour 4 read 25psi. That looks like normal pump bleed down to me. And I pulled a plug and it's wet. After talking to my brother in-law (he is a mechanic) he think the problem is in the distributer. Any thoughts?

MrWillys

Put a noid light on it to see if the injectors are pulsing while cranking. Pressure test sound good.

leesvet

I don't know how bro n law figers that,

but I doubt it. You still CANNOT flood an EFI engine if it has NO SPARK. Can't be done.
Impossible.
Leakdown rate is OK. Its not bad injectors mechanically....
that leaves, ELECTRONIC FAULTS. Shorts, grounding, etc. Remember this above all, This is a Bank fired system. one shorts, the whole bank shorts. Even on LTs. The inj circuit is very simple...a single driver in the ECM (later they got a 2nd) that has 2 paths, that are each split into 4. There are your 8 injectors. Now, short 4 of those so they all dump and stay open when there IS a RUN signal from the dist, AND pre-tension from the pump and THATS how you can flood a GM EFI engine. Short all 8 and you can watch the gas gauge drop as you crank the engine.
You DID sniff the dipstick, right?
Assuming you verified spark during cranking, even wet plugs should get it to rumble and TRY to start,. but if the spark is WEAK it may not fire, BUT it still cannot flood the engine even if a weak spark is present.SO, the spark is unlikely to be the source problem.

Something is AFU in the injectors. Short, inj that are too big, something is wrong.
This engine control system will NOT ALLOW fuel pump operation to KEEP fuel pressure UP, until the engine actually fires and runs ! the pump charges the rails for 2 seconds at key ON. Then,. the pump cannot run again until the signal from the dist comes that says its running....No signal, no mo gas.
It takes about 2-3 seconds to use that initial fuel charge or pre-tension. It will drop from 40 down to 20 very quickly and at 20 psi, that won't even spray out of the inj nozzles ..
The system is designed specifically to prevent flooding. If you want, d/c the fuel; pump, after the rails are charged. Connect the gauge. Crank the engine and WATCH the gauge closely....you can see EVERY inj cycle/pulse and you can see the pressure fall several lbs with every rotation of the crankshaft...it only takes a few cycles to use that small amount of fuel; and its no where near enough to flood the engine. Its designed to prevent that.

Read your FSM. They go into detail about the design intent of the system and its safe guards. Then go thru the electrical drawings and you can see the links between the systems that are described.

if someone has installed BIG injectors that do not belong there, yeah, maybe. or messed with some other part of the system somehow. Wet plugs mean raw gas and there are only 2 real ways that can happen in these EFI engines...a blown regulator or shorted/damaged fuel injection circuit or injectors.

ccorvetteracing

I finally had some time to work on the vette. This is what I did. There is no ECM & CCM codes. All fuses are good. The ECM and the Hypertech chip are good. Spark plugs have spark. Plugs are wet with fuel but look good and are gaped to factory service manual specs. And there is fuel in the oil, not a lot but some. So I believe that all of this leaves me with the problem is bad wiring or a bad fuel pressure regulator. But I'm not sure. I'm thinking about buying a ac delco FPR and see what that does. Any thoughts

desertmike1

Have you checked the Vacuum hose to FPR for signs of fuel.