88 2.9 losing prime

samwyse · Dec 1, 2015

There's some background, I'll give it in advance so anyone who has some ideas has the full story.

I replaced both fuel filters (inline and cartridge) in my 1988 4x4 xlt 2.9 Ranger in August of 2015.

Mid October I develop a gas leak near my cartridge filter.

Last week I took it apart and found the o-ring seal was crimped, likely cause for leaking. I replace cartridge and o-ring. That night, thanks to TRS, I learn that I have a fuel RESEVOIR to which I had somehow fit a cartridge filter into. To top it all, the filter was leaking worse.

So I pulled it all out again, pulled out the cartridge and used Permatex liquid gasket (fuel safe) to seal the reservoir.

But now my truck doesn't have fuel available when I try to start up after sitting than more than 20 minutes. It takes about 5 seconds of starter before starting.

Thoughts?

adsm08 · Dec 1, 2015

The anti-drain back check valve that keeps the system from losing it's prime is in the reservoir unit. You probably damaged it.

RonD · Dec 1, 2015

Turn key on, count to 3, turn key off.
Repeat 3 times

Now try to start

In fuel injected Fords the computer only turns on fuel pump power for 2 seconds when key is turned on, so if fuel pressure was lost the engine would be very hard to start.

The 3 ON/OFF cycles primes the fuel system 3 times(6 seconds), this will build up pressure to 30psi, where it should be if it was holding pressure

samwyse · Dec 1, 2015

Hi RonD

I've tried this, it sort of works, the starter still has to work a bit before the engine catches. I was trying to dig for info before posting the question. I'm still getting used to TRS forum layout. Alas, here I am, still asking the question

.

RonD said:
Turn key on, count to 3, turn key off.
Repeat 3 times

Now try to start

In fuel injected Fords the computer only turns on fuel pump power for 2 seconds when key is turned on, so if fuel pressure was lost the engine would be very hard to start.

The 3 ON/OFF cycles primes the fuel system 3 times(6 seconds), this will build up pressure to 30psi, where it should be if it was holding pressure

samwyse · Dec 1, 2015

adsm08 said:
The anti-drain back check valve that keeps the system from losing it's prime is in the reservoir unit. You probably damaged it.

I can see that happening. For some reason the first two times I took the reservoir off I managed to do it without dismounting the plastic unit where the return line goes back to the tank. The last time I had to remove it in order to get the cup off. I think this was because I accidentally wedged electrical lines against the frame rail.(who puts electrical in the same frame rail as gasoline?!)

Should I replace the whole unit to fix it?

RonD · Dec 1, 2015

Reservoir was there during transition to Fuel injection, in tank fuel pump has good flow but only 9psi of pressure, it was for carburetor engine, so Ford added high pressure pump in the frame rail which was needed for fuel injection.
Reservoir is there so pressure doesn't drop on startup, allows in tank pumps volume to catch up.
2.9l engine uses the same amount of fuel with carb or fuel injection, well a little less with FI, lol, so flow is the same, just pressure needed to be higher.

Point is you may want to change to '89 fuel pump system which just has 1 fuel pump in the tank, 1/2 the possible problems with 1 pump not 2, and no reservoir needed.
Check valve, backflow valve, is in the pump on the 1 pump system.

adsm08 · Dec 1, 2015

Actually Ron, that reservoir has very little to do with transitioning from carb to FI. And the 2.9 was never carbed, it was EFI from day one.

On the twin tank trucks that position was occupied by the diverter valve. The unit on the single tank trucks, along with the screwy two pump fuel system was used so they only had to make one set of fuel lines.

samwyse · Dec 1, 2015

adsm08 said:
Actually Ron, that reservoir has very little to do with transitioning from carb to FI. And the 2.9 was never carbed, it was EFI from day one.

On the twin tank trucks that position was occupied by the diverter valve. The unit on the single tank trucks, along with the screwy two pump fuel system was used so they only had to make one set of fuel lines.

Elsewhere I have read that the reservoir was for 4x4 models for extreme angles, as well as for Canadian "severe weather conditions"

Thank goodness I live in Beautiful B.C!

adsm08 · Dec 1, 2015

That is doubtful, as it was eliminated in 89 when the twin tank option went away.

88 2.9 losing prime

samwyse

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