TTMK5

i have an xj
but on my wifes grand cherokee it takes a while to start.
the dealer said it was losing pressure in fuel lines after 30 mins
so we replaced fuel pump. it still did it so we replaced it again.
and it still takes a while to turn over. (now on 3rd fuel pump)
if i turn it off and restart semi immediatly it starts right up but if i let it sit it takes an not normal amount of time to turn over. im afraid its going to ruin the starter.
any suggestions?

2 different garages cant figure it out.
p.s. no check engine light and no other symtoms

thank you for any help

jnicewan

Well it sounds like a fuel pressure leakdown concern. Have you tested the fuel press yourself? The factory spec for fuel pressure is 49 +/- 5 psi. The leakdown specs is about 5 psi in 5 min. Most of the time if you have a leakdown concern you will see pressure bleed off rapidly, but not always.

You can get a fuel pressure guage at most auto parts stores, and most guages will not require an adapter like some vehicles/makes. Just screw it into the fuel rail test port and see what you got.

Another thing I would probably go ahead and do is clean the throttle body plate and IAC valve and air passage/port. I usually take the IAC off to thoroughly clean it. and open the throttle plate to clean the throttle body using a old tooth brush for both

TTMK5

the dealership did a leakdown test and it states when running its at normal pressure of 60 psi/ shut off and lost 30 psi in 30 mins

what else do you think it can be? theres little to no chance that
there was 3 bad fuel pumps so, what the heck?

thank you jnicewan

jnicewan

There are a couple things to look for, I would want to put a guage on it myself and see where the fuel pressure is at when its cranking. Even if the fuel pressure leaks down sitting it wouldnt seem like it should take too long to crank/start. I have never seen a leakdown test that measured specs at 30min, Dealers/manufacturers would be replacing a lot of fuel pumps if that was the case.

There could be an injector thats dribbling and leaking when you shut it off, this is harder to believe, but more believable than a 4th fuel pump. There really is only 2 things that can cause leakdown without having an external/visual fuel leak and thats the fuel pump and injectors. Only thing is if a injector, it will leak fuel into the intake which usually causing a rough start, black smoke etc and/or engine misfires after running, worse case would be hydolocking the cylinder with the leaking injector.

Untill you are certain its a fuel pressure issue (still) and without knowing the year/eng data. You might have a sticking IAC or gunk in the throttle body. At least this is usually a free and easy thing to eliminate with a can a carb cleaner.

TTMK5

thank you , well, like my 98 cherokee ill have to clean the iac.
the lot we bought it off of (mistake cause his garage doesnt know how to work on jeeps, he had it more than us since november) they claim they put new injectors and coil pack and ecu. they didnt flash it. missed the wire harness for fan shorting on a bolt causing a code, forgot to chang an o2 sensor, put on cheap loud school bus brakes before we bought it and replaced the fuel pump 3 x.
ill take your advice and do all this myself and start weeding things out. i appreciate your help. im hoping its simple like the fuel press regulator and not injectors or bleed valve in the tank.
thanks again man!