Ok guys, I have a 88 xj 4.0 and the guy i traded said it needed a fuel filter (replaced). And it still hesitates but only seems to happen when she is low on fuel and/or when im on the trail (fuel getting stirred up while wheeling), now im thinking that I have trash in the tank. What do you guys think? HELP PLEASE!!

 

It could be fuel.. crap in the tank or the siphon hose on the pump eroding... I would pull the pump and investigate. When you pull other put a new trainer on it.

 

Check fuel pressure WITH a gauge when symptomatic. You need 31 psi of pressure for the engine to be happy. Then disconnect the vacuum line leading to the fuel pressure regulator and the pressure should jump to approximately 39 psi.

Good data = good decisions. Test your way to a solution.

If you buy a new pump, try to find a Bosch. They are the best in the business when it comes to fuel pumps. Stay away from Airtex fuel pumps like the plague. I (and lots of others) have had nothing but problems with them. They are a low price point choice for a reason.

 

yeah that is kinda what i figured, thought maybe it could be a vacum hose but then it would do it alot more often then just on the trails etc. I will try this way first.

Thanks Tj, I dont have a symptomatic but maybe I will hunt one down.. kinda on a budget. Unemployed

Thanks guys!