Martian

I have been attempting to track down the root cause of a fuel leak on my 1999 Grand Cherokee and I noted that the petrol was running down between the petrol and the LPG tanks and then dripping onto the floor.

I have since dropped the tanks, (just enough to see and access the fuel pump assembly), and noted that the fuel line, (that runs from the pump to the in line fuel filter - just above the rear axle), was wet due to fuel running between the rubber pipe and the external textile covering.

After removing the pipe I noted that it was badly perished so I have replaced it but now I note that the fuel is seeping out from the quick release connector that connects the fuel line to the fuel pump.

I have since tried two other, (second hand), fittings and I have even secured the fuel line directly to the pump feed and on each occasion fuel continues to seep from this connection!

I am sure that I can't be that unlucky in having three faulty connectors and I have checked the pump port to ensure that it isn't badly scored, (it isn't), so I am beginning to consider a more 'esoterical' cause.

Is there a possibility that there is no pressure relief, (my tank has a return feed connected to the rear of the tank), and this is resulting in the connector 'o' rings being subjected to a much higher pressure than they are designed to handle?

I believe the 1999 GK should have the pressure relief valve built into the top of the pump assembly - yet there is definitely a fuel return line going back to the tank?

Interestingly enough I note that there is NEVER any hiss, (or indication of any pressurisation), when I remove the fuel cap and this reinforces my latest theory and could indicate that the fuel return is blocked and the pump is delivering maximum pressure to the injector rail?

Has anybody experienced any similar issues with their fuel delivery systems I wonder?

I could have stripped and rebuilt the top end in the time I have been battling with this 'simple', (but somewhat frustrating), problem!

If only it was an electronic problem I would have sorted it in a couple of hours!!

Any advice and/or assistance greatly appreciated as I can't afford to waste any more gallons of fuel each time I prime the system!

dave1123

I'm sorry to say it sounds like you're talking about a multi-fuel system that very few people know anything about, over here, that is. I would think there must be a pressure relief in the petrol system when you're running on LPG that may not be working.

Martian

Dave,

Many thanks for your comments as I guess that you chaps don't have to worry, (quite as much), about the price of petrol as we do on this side of the pond!

I am hoping that the LPG control mechanism isn't that clever that it, (mechanically), controls the fuel return but I suspect that it may kill the pump voltage once the LPG kicks in.

Even if the electric pump is allowed to run, continuously, (when the vehicle is running on LPG), this shouldn't be a problem as this is what the pressure relief valve mechanism is designed to deal with - hopefully!

I have, temporarily, converted my Jeep pump assembly into a pond pump as I have placed it into a bucket of water and attached the fuel feed line to a length of hose that returns the water to the bucket.

I have stripped and cleaned the entire pump/regulator assembly and I have also blown compressed air through all three ports of of the Regulator.

When I energise the pump I get a healthy flow of water running through the hose back to the bucket, (with no seepage of fluid through the connector), and I cannot get the connector to leak even by occluding the feed line.

There is a possibilty that my blowing compressed air through the regulator may have restored normal operation, (I had a very similar issue on a Honda Blackbird that left me stranded in Scotland several years ago), hence it now behaving itself, (fuel was pouring out of the connector when it was fixed to the car - even with the engine running, (hence my suspicion that the fuel line was running at max pressure).

Unfortunately, (bad luck or my heavy handedness), the metal fuel outlet port, (on the regulator), is now weeping where it is welded to the regulator casing so I can't put it back in the tank, (after ensuring all water is removed), to test my theory!

I now have two options: -

1/. Purchase a brand new Regulator for £45.

2/, Purchase a second hand complete pump/regulator assembly for £60.

I will make my decsion tomorrow!

The joys of second hand motoring!!!!