noob needs some direction with 87eta

[tbe30ll]

hi everyone,

So I have a 87 325e sedan 5 speed with 137,xxx.
the history of the car as i know it:
sat for ten years with a bad motronic
I bought it, replaced the motronic
rebuilt the head (lash is set to the loose side for now)
new t/belt and w/p
new bosch fuel pump & filter
new bosch plugs (oem)
new universal O2 (i hope i know how to splice wires right, lol)
thats all i can think of now...

-intake boot looks new.
-intake gaskets are new.
-Didnot replace the injector o rings (i should have but my set didnot come with them and the old ones were still soft)
-fresh fluids.

So, here is the problem, the car runs great, starts right up, idles great, pulls really nice but, after the car is warm and running for a while it falls on its face. Say at 2500 in second it will cruise just fine, but any throttle input will do nothing. the same thing in any gear, this will get progressively worse untill i stop the car and let it sit, 10 mins does the trick. It will run fine for 5 more miles or so. (more and more of the rev range is lost to this hesitation as it gets worse)

The plan for tonight is to drive it with my timing light hooked up and in the car to see if i am loosing spark(i doubt it), as well as my dvom on the o2 sensor pigtail to see if i am rich or lean as the problem presents it's self.

If anyone has any help, or direction i appreciate it!

Thanks,
Tom

[jlevie]

That sounds like it could be a problem with fuel delivery. Given the history of the car I'd suspect a layer of rust in the tank. As the car is driven that rust can get disturbed and collect on the inlet screen of the pump, choking off fuel flow. The suction will hold the rust in place until the engine is shut off for a while. At which time flow is restored.

Pull the pump/sensor and stir the bottom of the tank with a stick to see if there is rust in the tank. The fix for a rusty tank is either to acid clean and seal it or replace it.

[Gary Horneck]

You mention new fuel pump. Which one? The in tank pump or the main pump? The '87 has two pumps and will run like crap with the in tank pump dead.

[tbe30ll]

Jlevie: That does sould like a good possibility, I think I may pull the acess pannel tonight when I get home and check it out, or drive it and keep an eye on the o2 voltages.

Thanks for the solid direction.

[tbe30ll]

gary:
pressure pump, so between the two of you we are in the direction of the "lift" pump? ah ha.... how about a slight gurgling on the press pump from lack of flow in causing a little cavitation?

[tbe30ll]

I'd like to thank the both of you it turns out it was the ground strap on the transfer pump!
She runs as she should now, I just went with a new vega pump because I didn't want to fix that strap and then the pump go bad. As for the condition of the tank... Not the best but better than cars I've seen that sat for less time.