LS13

I have a 2011 Jeep Grand Cherokee Limited 2 wheel drive 3.6l.L
For some time I have had starting problems if unused for a day or two. The local repair shop said I needed a new fuel pump and they fitted a new Mopar replacement.
I still have the same problem, and I suspect that the pump was OK, and maybe I am losing pressure somewhere else...maybe an injector or something., The car runs perfectly otherwise.
Can anybody, give me some positive ideas on where to look next

dave1123

IDK much about the newer models, but if it has a remote fuel filter OUTSIDE the tank, The pressure regulator is probably in it. It DOES if there are 3 hoses coming from it. It seems careless to replace the pump without replacing the filter as well, but it's possible the regulator is leaking down.

How does it start after being shut down for 3 or 4 hours? If it staggers or smells rich, you may have a sticking injector. JMHO, but replacing the pump without doing a pressure test for leakdown is irresponsible and costly. A new Mopar pump is what, around $500? It wasn't the pump or you wouldn't still have the problem.

You can rent a fuel pressure gauge from places like Autozone. Screw it into the valve on the fuel rail and read the pressure, then shut it down. Watch the pressure for a while and see how long it takes to drop. You should be able to tell if an injector is leaking if you smell fuel thru the throttle body after it leaks down. It should hold some pressure overnight.

I'm not saying I have all the answers, but I gave you places to look.

LS13

Thanks for the info. The 2011 fuel pump has everything built in. I am working with the local repair shop here in rural Mexico, I don't know how much knowledge they have, but as a retired engineer, I am hoping that between us we can figure out what is wrong. Changing the pump, seemed like a good idea, but apparently it was not the problem. The interesting thing is, that once the car is running, it performs extremely well on the highway. I have heard some comments about an ASD relay, causing this sort of problem, does anyone have any knowledge of this?

dave1123

This may help.

The ASD relay energizes both the spark and injectors (and maybe the fuel pump) and is tripped by a signal from the PCM when it gets a signal from the CPS that the crankshaft is, in fact, turning. A loss of CPS signal turns it off and shuts down the engine. It also won't stay energized if the security system is engaged. It shuts down the engine in about 2 seconds. You can try swapping it with another relay. Try one of the headlight relays. They used to be all the same relay, but 2011, who knows?

Long crank times usually come from lack of fuel or a slow responding PCM.

Try turning on the key and waiting about 30 seconds to start cranking and see if it makes a difference. This will allow the PCM it "warm up". If that doesn't make a difference, try cycling the key on and off a few times before cranking. The fuel pump only runs for seconds when you turn on the key to charge the fuel system with pressure. It has no way of knowing whether pressure is there or not, so doing it several times may pressurize it. That way you'll know if the fuel pump check valve is the problem.

LS13

Thanks again, for the very useful info. The guy at the repair shop has now taken some bits off the main computer and gone into the Chrysler dealership in Guadalajara (about an hour away), he was to come back and refit everything last night, after they did whatever!!, and we will see if it starts without hesitation when I get there later this morning. I wil post the results later today.

LS13

Got the Cherokee back last night after they had taken the computer parts to Guadalajara. Don't really know what they did, but they said, it's fixed. Between my poor Spanish and their poor English, it's all a bit of a mystery!. Went out to the car this morning, with my fingers crossed, and BINGO! it started up right away. So apparently, there was some fault in the computer.

dave1123

They probably "reflashed" the computer, that is wiped the factory program and reinstalled it. My 2000 WJ was called back for this even though it was running fine. They tell me it's like when Microsoft sends you updates periodically for your PC. I'm just assuming that's what they did. I'm glad it worked.

LS13

So Far So Good! Whatever they did seems to work. I will leave the Cherokee for a few days now, and see if it starts up OK when I next try. In the meantime, I will be using my Wrangler (1999 Sahara) it is more suitable for the many daily trips that I do up the mountain trail. I now have a new fuel pump in my Cherokee, which I didn't need, and I have the original, that I assume to be OK, so I have a spare!! They charged me 9000 pesos for fitting the new pump, and made no other charges for taking the bits to Guadalajara, and getting the fix, so I guess, that's not too bad.
Thank you for all your helpful comments.