question for the fuel sys. savvy guys

[Uni]

q for the fuel sys. savy guys

Hello all,

I've got a problem with my fuel/evap system. Everytime I hit the road on a long trip (>75miles) at approx 75mph, there comes a time when I start getting what feels like vapor lock, the vehicle sputters and eventually stalls, the fuel pump starts to hum like crazy and I get a lot of pressure built up on the tank, so much in fact, that the vent hose for the tank starts to spew out liquid fuel. If I pull over and shut it down for 20min it all starts to work fine again. I've already put a new gas cap, fuel filter, and a new pump. I've also diconnected the tank's vent hose from the charcoal canister but with no possitive results. Does anyone know what could be causing this?

 

[Uni]

Re: q for the fuel sys. savy guys

Anybody?

 

[RichP]

Re: q for the fuel sys. savy guys

Almost sounds like the anti-drain back valve or return fuel line is plugged. What year ???

 

[Uni]

Re: q for the fuel sys. savy guys

91 Xj with 4.0 ho

 

[Uni]

Re: q for the fuel sys. savy guys

tttt

 

[RichP]

This may have nothing to do with it but the plastic tanks are prone to a fungus growth and need to be dropped and cleaned. We had this problem on our 89YJ. Kept dying like yours at hiway speed. Dropped the tank and wiped it out, there was some nasty black stuff in there that had almost completely blocked the sock on the bottom of the pickup. Ran good for a while then the carter BBD started acting up and we replaced it with a weber 551 kit. I also had a co worker at lucent that had a 94 or so XJ that kept eating fuel pumps, after the third one in two weeks the repair shop finally ordered a new tank and pump, chrysler quietly picked up the tab for all 4 pumps and the tank, seems some year models had a tank that was susceptable to gas causing it to break down and plug the pump which allows the pump to overheat as the fuel flow is what keeps those pumps cool, they had some kind of quiet recall on them.

 

[Matthew Currie]

I would look for a plugged vent line somewhere, causing the tank to become pressurized. As a test, try driving with the gas cap loose.

 

[Uni]

When I replaced the fuel pump, I did notice that the "sock" or filter on the pump was of darker color, but I did not think much of it, As for a plugged vent hose, I saw liquid/pressurized air mixture comming out of the hose when I disconnected it off the charcoal canister, so I don't think that the vent would be plugged, however, how can I check for the return line being pluged or the anti-drain back valve?

 

[Uni]

-ttt