Hello all. I just put on a new headlight motor and all works well now! But I have been working on the car for a few days now and noticed fuel in my oil. So i pulled all of the oil out, smells like gas. Saw gas in the FPR vacuum hose so I got a new FPR and PCV valve just in case. I just also did all the O rings on my fuel injectors. I turned the car on with a fuel pressure guage and i heard a squirting sound from the engine. It would hit 40 but immediately start falling. I am not able to run it since i have no oil in it right now. Took fuel rails off again and smelled for gas. I found two that smelled like gas and re-did the clips for them holding them too the rail. Is it possible i have the wrong size O rings? I don't know what that sound is that came from the fuel rail and now i am nervous. I ohm checked all the injectors and they're all 12.3 or 12.6. Any help is greatly appreciated. I will post pictures of everything if i get to it.

 

The factory injectors are known to have problems. They can get stuck open. Pull the rail and keep all the injectors connected to the rail. For this test make sure all the clips that hold the injectors to the rail are in place. If you have the aftermarket injectors that don't use the clips, you cant do this test. Otherwise, if all injectors are in place and secured by the clips, turn the key on to energize the pump and pressurize the rail. Check to see if any injectors are leaking. With the rail under pressure (KOEO) they should not leak.

 

Thats an awesome Idea. I will try that tomorrow after work! I'll update accordingly.

Thank you!

 

I would not pressurize the fuel rail with injectors removed (but clipped IN) from their mounts as that is a bit dangerous. It might sound good but the potential for disaster is there. Any time you have fuel under pressure and it gets released it vaporizes and become very flammable and extremely dangerous.

On my 1988 the leaky injectors all had darker/wet markings on them making it easy to find the problem units. Two injectors were leaking and 6 were not when I did the one on my C4 using air pressure to test the injectors.

I was able to verify the leak with pressurized air in place of liquid fuel. Then listen for the leak. All these test are really a waste of time as you need to replace the original injectors anyway.

What ever you do be sure to have a Big Fire Extinguisher handy if you want to test with gasoline. I don't take chances like that.

"Paranoia will destroy Ya"

Is your 1988 C4 starting okay when it gets cold? There is one more fuel injector used in your cold starting system in addition to the 8 on the L98.
It all started when I was fixing my EGR valve. It turned into a several month long project but the Corvette runs better!

Best Regards,
Chris

 

I have a 1996 LT1 corvette. But i was hoping to not have to replace the injectors atleast not yet. I agree that the gas trick is very dangerous so i will hold my breathe on that. I was thinking i may have put the wrong O rings on the injectors and gas couldve seeped past them when i pressurize the fuel rail. I did see on injector that was different then the other eight. I will try and post a picture of them. It actually had another O ring in the fuel rail when i took it out. Which i know

is not supposed to be there.

 

One went bad and they just replaced one with maybe a Bosch which is shorter and DOES require an extra oring. Dan

 

oh okay so i will put the O ring back and see if i keep pressure. Thank you for that Dan

 

Fuel injectors frequently come in matched sets of injectors. This is for consistency if nothing else. They are supposed to all flow the same precise amount of fuel each time it injects. It is important to have them in the ball park at least. When I learned I had a leaky injector I immediately ordered 8 new injectors.
It was ~$180 for the set of Bosch injectors from South Bay Injector up near NYC. Fuel Injectorsare cheaper on Ebay and Amazon but I wouldn't trust the quality of the parts enough to use them.

Attaching pressurized air to each injector at about 40psi I then held the injector over some baking soda and watched to see if anything was leaking. I was tempted to stick them under water to se if any air was leaking from them while under pressure but that might have hurt them so I did not try the dunking in the water.

You are right about the Bosch being a bit shorter than the stock injectors but it shouldn't be a problem. All 8 of mine are shorter Bosch units and they still work.

Good Luck and keep us up to date with how it goes!

 

Okay so i finally had some free time tonight. 1130PM to be exact. I went against my better judgment and removed the fuel rail and pressurized the fuel system. Immediately shot up to 39 PSI and slowly started leaking down. I checked each injector for any wetness and found nothing at the tips. I checked my brand new FPR vacuum hose and I'm 99% positive the gas i smelled was from the gas I already spilled on my hands. I then took the fuel rail completely off and smelled for gas everywhere and i may have found some near 1 of the fuel injectors closest to the send line. Heres the kicker, i just replaced the O rings on the top and bottom of each injector. To be exact I used these: https://www.autozone.com/collision-b...9212/79646_0_0
According to all the research I did and could find, these would fit like OEM. I have no problem spending max 200 on injectors (Thankfully I'm on Long Island so i will likely go thru Southbay)
I also just installed a new delphi fuel pump, a new fuel filter as well, so i thought it could be from there, but nothing I could see. I also wouldn't necessarily mind if it came from there because the reason why I'm going through all these hoops is because i have gas in my oil.
For sake of covering all my bases, is there anywhere else I could be leaking vacuum? New PCV valves and grommets, new FPR, new pump and filter.
as a quick aside, I misplaced my schrader valve cap and cant find a new one for the life of me. Any ideas about that would be appreciated as well.
I know this is a long one, and i truly appreciate those of you who have helped so far.

Thanks,
Cam

 

Hello again CAM!

I don't have a cap on my schrader valve either, just keep curious folks from pushing the center pin while your hood is open. My schrader valve doesn't leak anything with the cap off the valve

What does the vacuum gauge indicate when you check it? The older C4's had an EGR Solenoid that controlled the EGR valve by controlling the vacuum going to the EGR. These were notorious vacuum leaks as they were hidden under the plenum on a stud that attaches the thermostat housing. On the later C4's like yours I do not know the vacuum system but if you look under the hood there should be a emissions diagram showing the routing of the emissions hoses. Using that diagram you should see most of the vacuum hoses and be able to verify that they are not crumbling like my old vacuum lines did.

If you have cruise control then check the switch that is connected to the Brake pedal switch under your dashboard and see if there are any leaks there. I might even go so far as to cut off 1/2" of vacuum line from each hose to ensure a good connection. My cruise control solenoid was also leaking air into the vacuum system.

If you are still having issues with your vacuum I would close off every port and then hook the vacuum gauge to the engine and go from there. If you have good hearing that should help. I don't so I use my kids hearing for me.

South Bay is actually on Long Island if I am not mistaken. They are good folks to do business with. You might ask them about the schrader valve cap that you are missing.

 

I will 100% take a look at al the vacuum lines when I get home. I do not have a vacuum gauge so I guess I will pick one of those up. I was under the impression that the fuel system didn't correlate to the vacuum system at all. In other words, I thought the fuel pressure wouldn't be affected by a vacuum leak elsewhere. Like I said, fuel pressure shoots up to 39PSI then immediately starts dropping. I don't remember seeing a diagram of the emission lines under the hood but i will look again, or google a diagram.

 

I am not an expert but if it is not your regulator or injectors is has to be at the fuel pump. Unless you have a line leak which would very soon be apparent. Dan

 

Im hoping its not the fuel pump, the fuel pump is brand new. I check the fuel lines and didnt see any leakage. Ive also heard, ( I forgot what it is called, but the part that is attached to the fuel pump that dampens the fuel flow) that goes bad and to just replace with a hose. Im truly at a loss at this point without installing new injectors. Any way to test them to see if any air is getting through?

 

You're thinking of the "pulsator" in the fuel pump area line. GM part #25094266 - or AC Delco fuel "dampener" #FP27. Usually replaced with a length of fuel-immersion-safe rubber hose. That has been seen to cause some of the symptoms you're talking about. Forum search here will help...

 

Yes! Thats what I meant. I have a piece of hose for it since it came with my fuel pump. I will take the pulsator off and change it for the hose. I'll search the forum on how to safely take it off.

 

There is also a check valve IN the fuel pump I am almost certain. Yes, you can send your injectors to FIC to be cleaned and checked but I would just get a set of rebuilt bosch. Dan

 

I will check too if possible. Thanks for the insight

 

Unfortunately I didnt get to work on the car tonight but i had a thought. When I changed the fuel pump, and took off the gas tank cover bolts. It was unbelievably dirty. Could it be possible that air is escaping their as well? Would RTV be a bad idea since its just metal bolted onto metal? Tommorow after work, I'm going to swap the pulsator with a tube and hope that works.

 

That would have nothing to do with fuel pressure. Dan

 

Yeah i figured that was a shot in the dark. Will update tonight. Thanks