Help with what I think is a fuel delivery issue

[mazing3]

Hi Guys,

I'm new to the 928 world but very well versed in every inch of 911s. Seems like little of that transfers. lol.

My 928 is a 78.
I had been chasing an over heating problem that eventually led me to a cracked expansion tank issue. I pulled it out, took care of the cracks with fiberglass mesh and resin knowing full well that was way over kill but after going through what it takes to get it out I had no intention of ever doing that again. During that process I took the right bank runners off and spent some time looking around and replacing all the vacuum and heater lines I could see and reach. The car is amazingly original but after all the things I have had to do to it over the past 6 months I have realized that TOO MUCH of it is original from a mechanical standpoint. I think you get the picture.

After I got it back together I ran it parked just long enough to get the temp up for burping, bleeding, etc... topped it off again and then went for a drive. It pulled better than before and generally felt "happier." Then for no good reason 1.5 miles into that drive it died. I do recall seeing a bit of blue smoke at the time as well. Not fumigating necessarily bit enough to notice it in the rear vies. Brought it back via flatbed. First tow truck experience with her so now that is out of the way.

It cranks fine but it just won't fire and there are none of the early sounds of combustion. Leading me to think it's a fuel issue. It's acting like it is out of gas, but it has 3/4 tank on the gauge and I know when it was that I last filled up so the gauge is accurate in that regard.

Before pulling the expansion tank out it drove fine. Always fired up right away and no issues. Except for the over heating part. My initial thought here is that I must have inadvertently disconnected something I shouldn't have or possibly pinched a line some where.

I was a little frustrated by all this after thinking I finally got it sorted from the over heating so I really didn't spend any quality time looking for answers in there today. I just don't know these cars that well yet so I am not sure where to look. Though I do know my way around my 911, I built the motor with carbs so never really learned all the finer intricacies of CIS.

I left the shop with it on the lift and will be heading back over tomorrow to try to figure this out. What kinds of ideas , thoughts, known issues, wisdom might you guys have as to where to focus and how I might be able to track this down? I do recall reading there was some kind of connector or sensor behind the air box and I definitely spent some time banging around back there as well.

I know we all love pics, but the pic I have on this computer isn't terribly flattering but it is a pretty good depiction of how it has looked for the past few weeks. I'll get some other ones up soon.

Thanks for your help! I just want to get back to enjoying driving this beast!

Thanks again!

[AirtekHVAC]

Could be the green wire.....the ignition module, which is one of the only electronic parts on the car ( one reason I like the OB's)....a broken or cracked rotor button, a jumped or broken timing belt.....its late, and I don't sleep much, so I am a little groggy....I'll come up with more stuff later.....I had quite a bit of troubleshooting myself trying to revive my old girl......

[mazing3]

Thanks Ron. Get that brain some rest.

After what I've seen in there in terms of the PO's interpretations of maintenance, I'm getting on the timing belt anyway the second I can get my hands on one Monday. Gotta be near it's end. I'm now putting the rotor button and green wire on my "take a good long look at it" list too now so thanks.

When the ol' noggin charges back up, the behavior really does seem to feel and appear like I ran out of gas. But didn't.

[AirtekHVAC]

What is your vin? Mine is a VERY early 928, and there is a fuel filter in the tank, a fuel pump at the tank, another fuel pump in the passenger fender well, a fuel accumulator in the fender well, and another fuel filter. Any of those could be your culprit as well. If you have the same setup I have, and one of the pumps is out, you ain't goin nowhere.

Good thing, is your engine is a non interference, so no biggie if the timing belt broke, all internals should still be ok. Go ahead and get a new wAter pump as well. I have not done my timing belt yet, but I am highly leaning to getting Kens "porkensioner" , in lieu of the factory tensioner....make sure your tensioner is good, or go ahead and replace that as well.

Lots of good help here, but I think I am the only one who gets on over the weekends...lol...

Check out my resurrection thread....lots of good info in there....

It's alive!!!!!

Feel free to call me if you have any questions....I have some other ideas, but let's check some of these out first.....(704-658-4114).

Good luck!

[The Deputy]

My immediate thoughts on this would be loss of ignition. Since you say you saw smoke/fumes coming out of the rear. Most likely this would be unburned fuel...so I'd go to the ignition side of things...since you are seeing the remnants. Although, a broken timing belt could cause similar results.

Not saying it couldn't be fuel related...and Ron may be on the right track...and you would surely want to elimate it from the possibilities for sure.

Keep us posted and good luck.

Brian.

[AirtekHVAC]

Ignition switch also comes to mind.....

[Awaino]

Have you checked the fuel pump and fuel pump relay? The relay was my first problem, almost towed home for that one.

[AirtekHVAC]

Good tips...for some reason, it thought you jumped the relay out...re-reading your original post, the fuel pump relay would have been my first recommendation....could also have a bad pump, as I mentioned also, especially if you have the dual pumps, like I have....1 of mine failed, causing me a little grief.

[mazing3]

Thanks everyone for the ideas.

I fixed it.

It turned to be something very very idiotic.- simple and idiotic. While I had the air box cover off a piece of hard rubber from something fell into the air metering valve and was basically wedged in in such a way that the plenum couldn't move up and down. So this would send a signal to cut off the fuel. Like I said, idiotic but free to fix issue.

Sheesh.

Thanks again.

[AirtekHVAC]

Hey, it's always the simplest things that get us. Congrats. Don't forget to replace ALL the rubber fuel line news ASAP.

[mazing3]

definitely will. Thanks.

[The Deputy]

I hate the self inflicted stuff...but it happens...nice find. Always makes sence to go back over an area you've had your hands in...when trouble rears its ugly head.

Brian.