Hi again!
My jeep suddenly decided not to start. It cranks but develops no fuel pressure at all. I tested with a gauge on the valve on the fuel rail and got 0 PSI

So, taking advantage of the handy hole someone cut in the boot floor before I owned the Jeep, I started looking at the other end of the fuel system. The pump doesn't seem to run. There's a very brief whirr when you go to posn2 but with the fuel pipe off, nothing comes out - even with the fuel return valve thing popped off the top of the module.

I tested the voltage between Green/White and Black and it's 0V until the jeep cranks - then I get 11V (the battery is pretty tired now after all the cranking).

Should I be changing the fuel pump (it's only about three years old) or should I be investigating the electrics? I thought that the fuel pump should run when the key is in position 2, but I might be dreaming that?

I'm a bit stuck

 

The fuel pump should run for about two seconds when the key is initially turned to ON (before cranking the engine), then when the PCM sees the engine rotating it will activate the fuel pump relay to power the pump.


You should hear the pump running for those few seconds before cranking the engine. If you are getting battery voltage to the pump when the engine is rotating then I would say that the pump is defective.


The recommended fuel pump module assembly is the Bosch brand (expensive) or the Carter brand. Stay away from other brands, like Airtex, as they are known to suffer crib death.

 

I assume you've changed the fuel filter and that it's not completely plugged but it sounds like your pump is dead. The pump primes when the key is turned from OFF to RUN for approximately 3 seconds. You should get pressure on the rail at that point. If you're hearing that "whirr" and have voltage, it sounds like the relays are all doing their job and that points to the pump. The pump should run continuously when the key is turned to START so that makes sense that you have battery voltage while cranking.

I would charge up that battery too before getting too involved in other things.

OOPs-Saw CCKen was already posting when I posted. I agree on the Bosch but the first Carter pump I put in lasted only a few months. Switched to Bosch and it's been in for a few years now without incident. Don't let your old fuel tank run dry with whatever pump you have.

 

OK, that makes sense then. I guess the electrics are OK and the pump has died a premature death. I think it was a Bosch, but I won't be sure until I pull it out. I have a cheapo pump spare because I fitted an Airtex module with a better pump. Once I get the module out I'll see what state the pump and in-tank filters are in.

The fun bonus is that the hole in the boot floor is centred on the stock fuel pump location but with the Propane tank installation the standard pump is now about six inches further back and it's really hard to get the whole module out in one piece. Still, it's better than having to drop (both) tanks.

I'll check out the filters, something might have put strain on that pump. Would the fact that it runs while I'm driving on LPG be a problem? I don't know if would be fighting a lot of back pressure or whether it would just be pumping fuel round the system. I could probably look at a manual over-ride if necessary. (I don't run it empty).

In the meantime, thank you! I'll get on with fitting a new pump. The prices are scary over here so I might need to scout about

edit: http://www.ebay.co.uk/itm/Fuel-Pump-...25.m3641.l6368 could be a candidate?

 

Nightmare
I can't get the fuel pump module out. The gasket was tight going in and now it's stuck fast. I'm probably going to have to do something scary to get good purchase on the top of the pump module and drag it out.
The tank has a lot of fuel in it

 

It's actually better to have more fuel in the tank if there's sparks going near it. Less fumes in the tank.

 

If you are going to just replace the pump/motor I highly recommend that you change the pressure regulator/filter as well.


Fuel Pressure Regulator/Filter Assembly:



.
BTW, I made an access hole in my cargo bay floor to get at my fuel pump.



.

 

Holy Carp Batman - I'd be happy to picnic off that boot floor!
You've inspired me to tidy mine up, the sight that greeted me when I got the boot carpet up wasn't pretty. It all passed the screwdriver test but I think I'll do some grinding and spray it with some Electrox I have handy.

As for the fuel pump, I've bitten the bullet and ordered the full Bosch unit from RockAuto who will ship to England for reasonable money. This means I'm OK to mash the existing module when I try to pull it out.

I reckon I'll have to get a rubber mallet and a drift to make some holes in the plastic. Then I'll probably drive myself crazy trying to fish wire in one hole and out the other to get some purchase and pull the thing up as straight as possible. But I'll wait until the new module arrives before leaving a huge hole in the tank in July...

 

The issue I had with removing and installing the pump thru my access hole was the limited space to work. I had to use a special spanner to remove and replace the pump lock ring. I bought the tool off Amazon. Not cheap.

 

OK, the new pump is in It's a full Bosch module from RockAuto. Twice as much as the cheapest ebay option (complete with chinese instructions) but I've had it with fuel pumps. The old one was a Denso, which I though was a decent brand so I'm a little concerned there's something else going on causing pumps to fail. I'm going to investigate whether I need to fit a manual cut out switch for the fuel pump because my Jeep only uses actual petrol/gas while starting and warming up before switching to propane. I don't know if running a fuel pump constantly against closed injectors is a very good idea.

Anyway, the new pump does actually pump! I was able to check it easily because I've binned the old fuel line setup which was leaking and I'm waiting for some new line and connectors before I try to start her up and drive. I put the key to posn 2 and even on the 3 second prime the pump chucked plenty of fuel out of the regulator

Progress!
Kudos for RockAuto to shipping to England, Kudos to USPS to getting it here quickly and YouSuck!! to the Royal Snail for adding an extra 72 hours to the shipping time by making me wait for a paper confirmation of customs charges before I could log into the web site to pay up.

 

The fuel pump runs continuously and supplies pressure to the fuel rail. The regulator allows excess fuel not consumed by the injectors to return to the tank so I don't think it makes any difference if the engine is running on propane. Since you do start the Jeep and run for a little while, you are firing the injectors at a regular frequency. Should be ok in my opnion. If you were really keen, you could rig a switch to the fuel pump relay and shut it down when you switch to propane but not sure if it is worth the effort.