Slow start....

[Hockeyfan960]

My 88 cherokee has 170k on it and it runs great....with the exception that it takes 4-6 cranks for the engine to turn over...I have replaced all of the spark plugs and wiring and distributor cap, along with a few of the ingectors for the fuel system, but nothing seems to get the engine to turn over on the first or second crank... any thoughts...???

[Saudade]

Yes, relax. Mine does the same thing ('88 with 155K). Got new fuel filter, plugs, wires, cap, rotor, TPS, CPS (all changed for other reasons). Got good vacuum and fuel pressure. Timing is right on.

Since it always starts, I just don't worry about it. When hot it takes 2-3 cranks to kick, cold is 6-10 (or so).

[comtac]

Exact same with 89 cherokee. I think that I might be losing fuel pressure though. When it's running the fuel pressure is fine, but I think after sitting it loses pressure and takes extra cranks to start. Mine starts fine one it gets fuel. I haven't had time to test and verify this but..............

[dksob81]

check the Crankshaft position Sensor, i think that is ur problem.

[viper1861]

I think the check valve on the cherokee fuel pumps are problematic.
I remember someone providing a good diagnostic for this on the board.
I recently ran a test on my slow starter. I turned the key to on with a fuel gauge hooked up...the fuel pressure rose to 31 and then immediately dropped to just a few psi. I disconnected the fuel pressure regulator and the pressure rose wich is normal. The indication was that the pump was good but the check valve was letting fuel flow back into the gass tank.

I had my fuel pump changed just because I wanted to address the slow starts not due to and problem with the fuel pump actually failing. The check valve can not be replaced separately from the fuel pump.


Issues to think about....COST....the dealer will charge over $200 bucks for an OEM fuel pump without installation. A good mechanic will tell you go stock don't go with knock-off brands. I ended up getting a Bosch which manufactures some of the original pumps from Napa. The pump didn't fit well therefore, my mechanic that does metal work had to cut and adapt. I paid about $100 for the pump and 80 for ther labor to install it and am glad I didn't do it myself. There is no comparison between brands on pumping capability. I actually saw the stats and the Bosch pump which was part of the OEM assemply can pump up to about 2x the psi the knock-off brands due.

[Saudade]

Hey Viper, so how does it start now with the new pump?

My fuel pressure runs about 32-33 psi with the key one and engine off. The pressure holds after shutting off the pump.

[Bad_Wing]

FYI,

When replacing a fuel pump, make sure you thoroughly clean the fuel tank with a non-ammonia antibacterial soap. Mr. Clean, hot water and a coarse sponge is what I used successfully. Jeeps have a service bulletin out on bacteria (brown sludge) growing in the bottoms of their fuel tanks. This evil bacteria damages the internals of the pump.

[viper1861]

With my new pump installed my pressure runs at 32 and holds for over 20 minutes at that pressure.

Cold start it takes 3 turns and warm start one. So replacing the pump has been a major improvement. The remote start function on my keyless entry actually works now.