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Old 07-10-2018, 10:05 PM   #1
moustacio
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Default Car Died, Hot FPR (740)

Hey, I'm back with another problem.

This has been well discussed here, but I wanted to post to see if something jumps out at someone as obvious.

1988 740, b230ft, lh 2.2.

Scenario: drove about 120 miles in the mountains, 90* F, from around 9,000 feet to 5,000 feet. Car drove great all day, exit the freeway for my house and in the turn press on the gas and the car stutters then dies. Fires right back up and drove fine for the remaining 5 miles home. 1/2 tank of fuel by the time I got home.

Only thing that jumped out as obvious to me is all the relays, and especially the fuel pump relay and power windows relay (right next to each other), were hot.

I'll be doing some testing before work tommorow and will probably throw my back up FPR in fof the ride to work, but thought I'd post.

Thanks for any suggestions/insights and sorry for posting about a topic done to death here.
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Old 07-11-2018, 11:38 AM   #2
ZVOLV
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Bring a test light with you and probe the back of the fuel pump fuse to cig lighter ring as ground. When the prob is there, power to pumps? How about to the computer side of the EFI relay circuit?
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Old 07-11-2018, 04:24 PM   #3
moustacio
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Hi ZVOLV and thank you,

Yes, voltage is present. Haven't checked the computer side, I will have to find my wiring diagrams.

Had time to put a clear hose on the fuel sending unit to the gas filler to test the intank pump. The gasoline is coming out but is quite aerated/bubbly. I seem to remember a steady stream of gas last time I performed this test.

Q: The gas shouldn't be aerated coming out of the fuel sending unit correct?

Other than that the car is running fine for now.

Thanks for any help
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Old 07-11-2018, 04:28 PM   #4
Uncleknucklez
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This screams bad pickup hose on the in-tank fuel pump. Anything less than half tank will suck air if the hose is bad (it's no longer submerged and any cracks/holes are exposed)
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Old 07-11-2018, 04:40 PM   #5
moustacio
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Thank you for the quick response Unkleknucklez,

Looks like I'll be going in to the tank.

It's funny I was in there not long ago to put the accordion style in-tank hose and it ripped, I'm assuming, upon installation. Put back the hose that was on there before. I'll have to pony up for the submersible hose this time.

The aerated fuel hitting the main/high pressure pump must have made the pump work harder and draw more current? Thus, heating the FPR as well?

Thanks again
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Old 07-11-2018, 05:48 PM   #6
ZVOLV
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One wire that comes to mind is the blue/yellow wire that powers the MAF. Really easy to peel back and check for current with a light to co form if the EFI/FUEL PUMP relay is working.

Another idea is check for spark when it's dead. Click my sig.

And bring a can of starting fluid to blast into the throttle body or just in the IAC hose hole. Then see if it starts. See my sig.
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Old 07-11-2018, 06:44 PM   #7
moustacio
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Thank you ZVOLV,

The car runs but thanks for the info, I do appreciate the help.

Yep, the in-tank hose connecting the pump to the outlet was torn and in bad shape. I should have known better after reading all the threads that say to use proper 30R10 submersible fuel line. What I had in there was separating, mushy, and in all aspects just done for. Strangely the fuel hose that was in there (30R6 I believe) lasted almost a decade.

I'll get some submersible fuel line tonight and follow up here with the results.

Thanks again guys
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Old 07-11-2018, 07:07 PM   #8
moustacio
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Question if y'all don't mind:

Can I use a hose clamp to secure the pump to the sending unit?
The two metal clip type things don't seem to be holding the pump anymore. Or maybe I'm missing something on how it should go together?

Thank you
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Old 07-12-2018, 12:46 PM   #9
EivlEvo
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Quote:
Originally Posted by moustacio View Post
Question if y'all don't mind:

Can I use a hose clamp to secure the pump to the sending unit?
The two metal clip type things don't seem to be holding the pump anymore. Or maybe I'm missing something on how it should go together?

Thank you
In a perfect world it's in a "perfectly vertical" position to aid the life of the pump. I don't think hose clamping it would be bad. It just needs to not move really and be cooled by fuel.
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Old 07-12-2018, 11:03 PM   #10
moustacio
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Thank you EvilEvo,

Got everything back together this morning before work and all is well in the world.

Thanks everyone for the help
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Old 07-15-2018, 06:00 PM   #11
lummert
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When my 88 765 had this issue it was caused by a dead in-tank fuel pump. This was realized after the main pump went out due to overheating.
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