I've posted a picture of my #1 and #3 injectors on my L98 engine. Notice the black area on the intake manifolds and the outer casing (green part) of the #1 injector (hard to see).

I'm just wondering because my gas mileage has been horrible lately, and I have reason to believe the fuel system is loosing pressure quicker than it should (fuel pressure test).

Does this look like fuel leakage?

 

Could be. That's similar to what mine looked like after one of my Accels cracked.
How fast is the pressure dropping?
I actually had a puddle of gas sitting on my manifold.

 

Well, I was having some trouble a while back with my car not start when it was hot. So I did two fuel pressure tests: one with the engine cold, and another when it wouldn't start.

Here are the results with the engine cold:

00 minutes: 41.0 PSI
05 minutes: 36.5 PSI
10 minutes: 34.0 PSI
15 minutes: 31.5 PSI


And the results with the engine hot (and not starting):

00 minutes: 43.0 PSI
05 minutes: 26.0 PSI
10 minutes: 17.0 PSI
15 minutes: 11.0 PSI

Oddly enough, I haven't been having the starting problems any more. My fuel tank was leaking, so when I had the tank out I went ahead and changed the fuel pump at the same time. Who knows, mabye that was where the bleed off was happening.

However, like I mentioned earlier, the car is getting horrible mileage and something about the stain on the injectors and the intake manifold reminds me of the stains I had on my leaking fuel tank.

Do I just need to be looking for new O-rings?

 

with all the work involved in repalcing the orings i would definitely not leave those same injectors in there. those are multecs (prone to fail). i would either get some good, used, KNOWN working LT1 injectors or some SVO's in there. i been down that road before and it's too much work just to change orings and still have to worry about crappy injectors(that will fail). i replaced mine. you won't have to worry about the injectors or the gaskets being bad and can rule them out, if infact, the problem does persist. best of luck. have u checked the resistance on those injectors in the past trying to find out what's going on?

 

Mystikkal: I have been toying with the idea of getting new Accel injectors, but just haven't had the money. I would have picked up some used ones--but I know that both the LT1 and SVO injectors are 24 lb/hr injectors (as opposed to the stock L98's 22 lb/hr). I don't have the equipment to reprogram my PROM, so I'm not sure how I could make that work.

But, you're right: I do need to get new injectors, somehow.

 

24lb injectors will run you a little richer but nothing that's gonna affect how your car's running. Changing the prom is nice but for a 2lb difference you'll be fine. I read on here somewhere that the computer can compensate for a 20% difference in injector size. That may be true. I was getting the same mileage with the 22# injectors in my car as I'm getting with the 24#. This was with the stock 22# programming. I've since changed it to 26 and haven't noticed a difference.
The only way to know for sure that your injectors are leaking is to remove everything in the way of the fuel rail, pop it up so that the injector nozzles are above the manifold, and pressurized the system. If they're leaking you'll see it and which ones at this point.

 

When I talked to Rich at Cruzin' Performance about cleaning my injectors--and after he told me dump my Multitecs in the deepest body of water I could find--I asked him about getting new injectors. The first thing he recommended to me was to get Accel injectors. He said that they will carry new 22# replacements and that they should be a direct swap. When I asked him about getting LT1/SVO injectors, I remember him saying that #24 was going to make it run too rich and that I need to get my PROM reprogrammed.

(Not saying you're wrong, Viprklr, just throwing that out there...)

While we're on the topic of fuel components leaking, I'm curious: could the fuel rails themselves leak? I'm thinking about the two pipes that connect the two rails to each-other. Are there O-rings where those pipes go into the rails that could/should be changed? I know I had my fuel rail sitting in the garage for a long time, and it got moved around a lot. Hopefully, I didn't loosen any seals in those pipes (although I did notice that there is some play there).

Thanks again

 

YES!!! they have orings everywhere. i HIGHLY recommend doing this. removing the fuel rail on TPI is a daunting task compared to MR or an LT1 intake. i re-did my fuel rail orings + injector origns with a GP soreson fuel rail + injector kit from Autozone. a few bucks if i remember. my old one's were cracked and looked frayed. so replaced them as well when i replaced the injectors. no need to worry about them for years to come .

 

Sancho,

Your fuel pressure loss rate looks fairly normal. A leaking injector would probably drop pressure much faster, and any injector leaking enough to affect mixture would drop pressure MUCH faster. Most likely you have a valve in the fuel pump seeping, or a slight leak at the disc/seat of the FPR, niether of which are an issue with that rate of loss.

None of that, of course, means that your injctors are flowing at the correct rate, but serious internal leakage is not likely an issue. The dark area around the bottoms of the injectors does look more like 'O' ring leakage. A new set of injector 'O' rings is usually about $23, and if you replace those, it would be a good time to do something with your injectors. I have also heard from Rich that servicing the earlier-style Multec injectors is seldom worth the effort. Perhaps you could find a set of take-outs on eBay or some other source, have them cleaned, flow matched, and ready to install when you undertake the project. The nice thing about that (other than peace of mind) is that you'll get good 'O' rings back with the injectors.

 

Any tips on how to change those O-rings? Do I just pull the rails apart and then the O-rings are exposed (and just press them back to reinstall)? From what I remember, those pipes just go straight in--no clips or anything.

 

I agree, but my Accel's were just leaking through the injector body itself. I could see it dripping onto my intake manifold. According to my fuel pressure gauge the drop was significant enough to make any readings worthwhile. It looked normal.