Bigokie

First let me say I am new to the Jeep community and this forum. Glad to be here.

I bought my son a 94 Cherokee 4.0. Had to put sensors in transmission right from start

We havent had it 2 days and it seems that it takes SEVERAL cranks for it to start. From what I have read, could be fuel pump or orings in pump. Does this seem correct? It might be letting fuel drain back to tank when not running and not keeping it "primed" ???? If this is the case how hard is it to drop the tank and do this?

If this sounds like another problem, please tell me where to start.

Thanks and I appreciate the help

David

DFlintstone

One thing to try. When the key is first turned on the pump will run for like 2 seconds. If you do that like, three times, then it starts right away, then your "poor mans prime" worked, and you are loosing fuel pressure while it's sitting. One deal I read said the pressure should not drop more than 20 lbs in 30 minutes. (sitting, off). The check valve in the fuel pump is a common culprit, although mine was more the leaking injectors.

One way I new to suspect injectors is that if I turned it off hot, then started it in 5 or ten minutes. (foot off the pedal), it would miss for a second cuz a cyl or two was flooded. Idk. Seemed that way. EDIT/ADDED That would be more pronounced after doing the prime business above^^.

94? I think MAYBE your pump is mounted on the front of the tank. (you can see a big ring way up on there). The newer I'm not familiar with, you need to pull the tank because it goes in the

top....so there's a start! And welcome!

SeriousOffroad

Sounds like a bad check-valve in the fuel pump assembly.

The fuel pump assy is mounted to the front of your tank and can be removed without dropping the tank.

Bigokie

Thanks guys. I appreciate the help. I asked a coworker who has one and he said maybe the orings on the fuel rail ?!?!?!?!??

I looked the pump up on O'Reillys site and it says its $175

The check valve is just a nuisance thing right? Hes not hurting anything except starter wear and tear correct?

salad

If you had issues with O-rings on the fuel rail you'd notice a strong smell and leaking gas everywhere.

If it's indeed just the check valve that's not really a big deal... just make sure he does the "poor mans prime" every time before starting to prevent extra wear.

JwL89XJ

^^^that x100 I had leaky injectors and you'd know it right away by the smell. One thing i did do though was accidentally break the molded hard plastic vacuum hose leading to the MAP sensor when I changed my injectors out maybe there's a problem with that if it's starting but giving fits to do so and you've checked everything else. That's what mine was doing till i figured it out. I also do the poor man's prime out of habit after I changed my starter. As I understand it the MAP sensor regulates the amt of fuel goes into the valves as you start the engine.

good luck!

DFlintstone

Yea, I agree with salad, it's no big deal. Yow long are you talking, and does priming it work? One thing, when mine was leaking through the injector(s?), it wasn't helping the mileage.

As far as leaking past the injector O rings, you can take a good look. The ones holding fuel pressure are there under the little bell like things on the rail, at the top of the injector.

I different issue, I had a bad lower one that caused a vacuum leak.

You might check rockauto on that pump, but stay away from Airtex.

Transition "sensor's", plural? There is the speed sensor, then solenoids. I only ask because I'm curious, leaning here.

XJ.89.Limited

One rule about the forum, say "grand cherokee" if you are not talking about the XJ cherokee. The only similarities are in the drivetrain. That is a big peeve of us XJ owners. Just a little heads up . But otherwise, poor man's prime works for me. My ol' renix likes to tease me a little before it starts. It has its own personality as I say. It's normal for mine to take a little longer because of the design, but the prime does help a little. Good luck with the fix! Just beware of the jeep disease. Once you get it, it doesn't go away .

Bigokie

Point taken on the specifics!

I told him the poor mans prime trick last night. Im at work this morning so he is supposed to text me the results. He's 17 so he probably forgot about 10 mins after I told him(they tend to have other things on their minds )

Ill report back if it helped!

Thanks again for all the help.

David

Bigokie

AWESOME site btw!!!!!

Firestorm500

Bigokie: You originally said it takes several cranks to start. Does that mean it seems to take a while, from your prospective, to fire off? Or does it mean that you crank, and no fire. You crank for a while again, and no fire?

Bigokie

Received a text from my wife that the poor man prime worked EXCELLENT! So it is a fuel issue not fire. Seems he will be doing this technique until the fuel pump goes out.

Thank you again everyone and I plan on being a regular here(lots of internet time at work at certain times!!!)

David

88 Thumper

Just a heads up on this, I have changed my fuel pump this way (without dropping the tank) & just pulled it off the front of the tank. It came out easy enough BUT, putting the new one in was a real pain! The main reason is do to the design of the pump assembly & the weight. There is not much to grab ahold of when you get the pump in the tank & you are trying to re-align, it wants to tip forward & give you problems. Maybe someone here has a trick for it that I was not aware of. I just remember it taking a long time to get it back in & a lot of cussing.

SeriousOffroad

Thanks!

Firestorm500

The mechanic who did the fuel pump in my '92--yeah just after I bought it--decided it was less time and frustration just to go ahead and drop the tank.