This has become the installation from h**l. The car is an 88 L98. Installation should have been straightforward, but TPIS instructions leave a lot to be desired.

I have everything installed and hooked up to the fuel lines but I am now running into a problem with leaking injectors. The injectors are the same ones out of the old TPI setup with new O rings installed, but they are leaking at the fuel rails BAD. Tried them with the old O rings and no difference. They worked fine in the old TPI setup. 20# preassure throws gas all over the engine. I have already ruined the nice paint job I put on the manifold, but I can get over that and re-paint the manifold later. I just want to get back to driving again.

Anybody got any experience with this? I called TPIS, but they didn't offer much help. I checked the bore diameter in the new fuel rail and compared it with the old bore diameter in the TPI set up and it is somewhat larger by .15mm, but that doesn't seem like eonough to cause this problem. Any thoughts? ANy suggestions?

 

Did you use the clips to enage the injectors firmly into the upper fuel rail?

Sounds to me like the fuel rail bolts are not tight enough holding the inectros in. The injectors should push in sort of hard to compress the o-ring.

 

Also, make sure you dont have the fuel pressure accidentaly jacked up to max.

 

I had mine apart to change injectors and could not get them sealed back into the rails no matter what I did. I spent two days on it and finally had it towed to someone who does this for a living Anyway, it takes him 2 days and a lot of nasty language to get it back together. Turns out there are a ton of different o rings and he went through a bunch of different ones until he found a set that sealed. For my Bosch 30lbs they are light blue????

 

Lube the rings up good with some grease!

 

I just swapped injectors today and have done it a few times in the past w/ the MR.

You must be careful when setting the rail on the injectors. It's easy to pinch the O-rings if the rail is not placed on the injectors nice and square and pressed firmly and EVENLY onto all four. White lithium is what I use for lubricant. Bring the rail to the injectors, hold it nice and square, test each injector for proper alignment to the holes, start pressing the fuel rail on and double check that they are all aligned correctly. I usually squat and look up at the bottom of the rail. When everything is lubed and lined up, press the rail STRAIGHT down onto the injectors. It should press on and when seated the bolt hole should already be lined up.

I know this sounds very basic, but you need to make sure you're not pinching the O-rings. Also, check them all now (o-rings) for tears and cracks. It is easy to damage them by pushing the fuel rail down slightly askew.

 

Totally! Lube those O rings with a bit of white lithum grease. Massage it in good and wipe off the excess. Line them up evenly and press straight from the top just like RainDelay states.

 

Thanks everyone for the thoughts. Keep them coming. O rings were replaced with parts from the Chevy dealer and were lubed with Vaseline, a trick I have used for years with no problems. I will try the white lithium but don't hold much hope that it is that simple. I have my TPIS fuel preassure gauge hooked up and have never gotten above 20# before we started leaking serious amounts of gas. The adjustment screw on the AFPR is almost all the way out.

I may be missing something here about alignment. These injectors are leaking at the top fuel rail. The depth of engagement is controlled by the lock ring. I have been installing the injectors into the fuel rail, locking them in with the ring and then setting the entire assembly onto the manifold and pressing all four injectors home. I don't see how you would put the injectors into the base manifold and then press on the fuel rail. You would not have access to the lock ring to rotate it into place. Please enlighten me. This is interesting but frustrating. This is my first experience with injection and although I have played with carburated engines for many years, this is a whole new learning experience.
Thanks everybody for your help and comments. Keep em coming.

 

I understand the problem is at the rails, but if I can offer this: Vaseline has a tendency over time to break down rubber O-rings causing a potential leak down the road. Some white lithium or a teflon based lubricant (get mine at the local pool supply house) is a little safer. Good luck in nailing down the problem

 

I was not aware that Vaseline would do that. Thanks for the input. At this point, I would just like to get down the road

 

i don't know anything about how the fuel rails are mounted on that intake, but would it be possible to slot the holes and move the rails closer to the injector bodies?

those bosch injectors are definitely shorter than the oem ones, btw. in most cases there's enough tolerance where they will seal, but i've even seen a lot of cases where the fuel side was sealed but the other end not (creating small vacuum leaks which led to idle/drivability problems).

-michael

 

 

If the O rings are true rubber (natural rubber), which I doubt they are, vaseline will "work" on them in time. I really don't think any supplier would provide rubber O rings for anything that has contact with gasoline. Gasoline on rubber O rings is sure failure and pretty quick.

Most O rings are TPR'S, thermoplastic rubbers, and are available in many compounds or variations that are suitable to specific applications.

If you or anyone can provide the compound of O rings generally supplied for fuel rail applications I have a background in hydraulics, pneumatics and plastics and can usually determine viability of a particular compound. Arkvette

 

Measure the hole ID, then measure the OD of the O ring on the injector how much difference is there?