Second post of the evening...

I have been chasing a fuel starvation/engine stumbling issue on my recently restored 84. While replacing the TPS sensor (twice), the recently installed 85 pump failed. I believe I remedied the situation finally last night with replacement of the TPS sensor and another new 85 pump, but ran into something upon re-installation of the pump/filler assembly, and want to check with forum members.

The filler neck/float/sending unit is also a new replacement. When I lowered the assembly back into the tank (with new pump installed) I noticed that the assembly slid ALMOST all the way down into the tank, BUT there was perhaps a 1/8 inch or so gap between the mounting plate and the tank mounting surface. Tested and refit several times, and did notice that there is a white plastic looking "tray-like" trough that the pump and bag inlet filter evidently fit in to.

End result is that it seems Im pressing the bottom of the pump slightly against the bottom of the tank or white tray when I snug the bolts through the filler neck plate and into the tank. Im thinking that since the inlet is on the bottom of the pump, pressing it into the bottom of the tank may restrict fuel flow into the pump.

Question: Should there be clearance or spacing between the bottom of the fuel pump and the bottom of the tank?

I drove the car tonight and happily it ran very strong, with none of the earlier problems apparent, but still I'm wondering if the install is correct. I assume the fault would be in the new replacement filler/sending unit being slightly too long.

Any thoughts/experience appreciated.

Thanks,
Gary

 

Hmmm, good question.

I have a new assy. w/ pump ready to go into my '89; waiting for temps to drop below 90s.

Hope to be doing the job tomorrow; will let you know what I find. In fact I'll try to determine the "depth" of the old OEM unit before removing it.

 

The 84 tank uses a bladder. Later tanks have a well. If either is loose fuel can sloush away from pick up at less than 1/4 tank. Sock needs to correctly installed so it doesn't contact float and should reach bottom of well.

 

My 84 has the sump in the tank so either mine never had a bladder or someone removed it!

 

Update: As mentioned previously, in my 84 cross-fire I replaced my failed 85 pump (yes 85, with the adjustable fuel pressure mod via Buccaneer's company), which failed during process of trouble shooting a fuel starvation issue. When I Removed the pump to replace, found the old pump sock had a layer of sticky gunk covering entire surface, which i now believe is some kind of residue/varnish in the tank despite my efforts to clean the inside of the tank as I restored the car after several years of sitting. I think this was the source of the fuel starvation issue and likely the failed pump as well.

So, installed new 85 pump, new sock, and car ran great. BUT, I noticed that when installing the tank sending unit it was slightly too tall ( approx 1/4" or so) and top plate was pushed down onto the top of the tank with the screws. This seemed odd, and I felt that pushing the pickup into the bottom of the tank was not a great idea. Seemed that it could lead again to fuel starvation, even more so if there was residue remaining in the tank.

Today 150 miles or so later, the issue re-appeared. So I think Im in the middle of solving 2 problems:

(1) Residue in my tank, and need for more complete cleaning. The tank is original, has the white plastic looking tray in the bottom, and also is plastic lined. Ive heard it called a bladder... Any brilliant ideas on how to thoroughly clean the tank (without removing if from the car, hopefully), would be highly appreciated
(2) A sending unit that is slightly too tall, and is pushing the bottom (fuel inlet) of the pump into the bottom of the tank. Ive since read that some owners observe buying sending units perhaps marketed as 84-96, and they are too long for the 84. One owner mentioned he had a unit made by VANS in his 84 and it was slightly too long. So Ive ordered another new unit from Zip, who claims they have the correct one-year-only part. Any more thoughts on this are welcome as well.

Thanks to all....