ZeroCherokee

Within the past couple weeks I've done a full tune up.

-New CPS
-New spark plugs and wires
-New distributor cap and rotor
-New IAC
-New TPS sensor

And last but not least,
-784 injector swap


I put the injectors in today, and it fired right up. Drove it for about 70 miles, stopped and got out. After about 10 minutes, got back in, and it wouldn't start. It took about 45 seconds, and three attempts to crank before it turned over. I also had to give it some gas.

Hour later, same scenario, same issue starting.

Anybody know what it could be, or how to fix it?

sthon

injectors could be getting heat soak, they could be leaking. Hard to say really. Obvious solution is to put the stock injectors back in.

Rearwardassist

Did you clean them all? Were they new or JY pulls?

salad

Could be heat soak. The connectors might also be bad. What year is your XJ? It's not in your post, title, or profile.

ZeroCherokee

I ordered them from a member on here who seems to sell quite a few of these. I was told they were cleaned and checked before shipping.

1999.

CCKen

Are you saying 'turned over', as in the engine rotating via the starter or are you saying running on its own?

Does giving it some gas mean you pushed the gas pedal down?

Have you checked the fuel pressure at the fuel rail? Should be 49.2 psi +/- 5 psi. Fuel pressure leak down after the shutting the fuel pump off? Should not drop below 30 psi for five minutes. If there is a rapid drop off there may be a leaky fuel injector or a bad check valve in the fuel pump module. Some fuel pressure kits you can rent have the hose set up where you can isolate leaking injectors or pump check valves.

Having to depress the gas pedal while starting may mean there is residual fuel in the intake and adding air by opening the throttle plate leans it out enough to start. A leaking fuel injector will cause this problem.

ZeroCherokee

Turned over as in running on its own.

Giving it gas was me pushing the pedal down.

The fuel pressure is fine also. I forgot to put in my OP, but the fuel pump assembly is also brand new. Less than 50 miles on it.

Should I just send these back then? Because I seem to be the only person that has had a problem with the seller on this forum.

ZeroCherokee

Bump.

Turbo X_J

Just out of curiosity what brand?

Pump pressure was checked at the rail using a gauge during this no start?

Had a solid nasty white spark as well?

ZeroCherokee

It was a Bosch assembly.

I was out on the trail when the no start was happening, so if it acts up today, I'll give it another go.

storm101

Did you reset the PCM at the end of your installation?

Give it a shot if you didn't, it's located towards the end of this write up.
https://www.cherokeeforum.com/f51/in...ap-4-0l-92149/

ZeroCherokee

I reset it again, still not helping. But now it's having the problem when it's cold. I went to start it this morning, and still took about 30 seconds.

CCKen

Do you still have the original OEM injectors you could reinstall to see if it makes a difference? If it does then I would return the 784's for a bench check to see if they leak.

ZeroCherokee

I checked to see if any of them leaked, and sure enough, #6 was. Swapped out my stock one, and runs like a top. Thanks everyone for the input.

pwb

How did you check for leaks, just interesting to know how to do it :-)