89 Jeep Cherokee

[w_steele808]

Hey guys, maybe someone can help me. I got a starting problem with my jeep, I have good fuel pressure at the rail, I have spark, I got all that. The only time it starts is when I spray starting fluid in the TB. It starts just fine when it's warm, other than that, it don't want to start at all. Any suggestions? I'm bangin' my head agianst the wall trying to figure it out. Thanks guys.

[72mino]

When trying to start it does it fire at all or just crank? Once it starts with starting fluid does it idle/run fine? Check the simple things, air filter, plugs, wires, cap, rotor (could have spark, but too weak until alternator is putting out extra voltage).

Dustin

[w_steele808]

It just keeps cranking. It runs fine after spraying the starting fluid, I put in a new air and fuel filter(and yes it's in the right way) new cap, rotor, plugs, wires. I'll check for spark again though, thanks.

[Saudade]

How did you test for pressure at the rail? Did you use a gauge? If so, what did you get? if not, you should get one and measure it. Depressing the schraeder and getting a squirt isn't good enough.

Also try turning the key on but not start, wait about 5 seconds. You should hear the fuel pump prime. Then turn the key off. Then try starting it.

[w_steele808]

Well, I checked the CPS (219ohms hot), and the coil, they were fine. So I'm gonna start leaning towards a fuel problem. I tried the turn key and wait 5sec thing, didn't work. So, I'm gonna test the injectors, the fuel pump, and the ECU.

If there's anything that anyone thinks I missed, let me know. Thanks to all for their help!

[w_steele808]

Well, tested the injectors, they were fine, got a new fuel pump and crankshaft sensor, put them in(both for under $90). But still won't start w/out starting fluid, when it starts it runs smooth. So, I don't know what else to look for. I'm gonna see if I can get a code reader and see if I get any troublecodes. If anyone has any ideas on what I can do, The help would be greatly appreciated.

[discnik]

Is this a Throttle bodied or multi port injection system ? The fuel pressure regulator could be just bad enough to where there is low fuel pressure, (Not enough to initially open the injectors), until there is ignition in the combustion chamber. You should check fuel pressure to insure this is not the case.

31 P.S.I @ idle

Remove vacuum line from fuel pressure regulator, If multi port injection, should read 39 P.S.I.

With out the vacuum line attached to the regulator pressure should be 8 - 10 P.S.I. higher.

[gtmud]

Ok, it sounds like you have a possible volatility issue with the fuel, or a weak spark. Stop and think what the starter fluid is doing. I would double check your grounds, and powers. The pcm gives the injector a ground to open allowing fuel to enter the combustion chamber. If it runs well after started then I would lean towards fuel pressure. Get a reliable gauge and get an actual psi reading. Also you can test this and the injectors by carefully removing the fuel rail w/ injectors attached, zip tie the injectors to the rail, remove the coil wire from the coil. Watch the injectors as some one else cranks the engine. You should see each injector spray a mist of fuel.( this is were getting the proper psi at the rail is important) IF you see a drible of fuel then you may have a leaking injector(s) causing your engine to load up on fuel and basically flood the engine. The ether( starter fluid) will over compensate for this and start the engine. It sounds like everything else is working correctly, CPS,TPS. Again, double check your spark at the plug! It should be a good blueish color, yellow or orange, replace the coil. ( oh, my 2 cents, stay away from advance auto electronics, they are very un reliable, reason for the cheapest price. Napa, auto zone, or dealer when it comes to electronics. opcorn:

[SINCITY192]

Originally Posted by w_steele808

Well, tested the injectors, they were fine, got a new fuel pump and crankshaft sensor, put them in(both for under $90). But still won't start w/out starting fluid, when it starts it runs smooth. So, I don't know what else to look for. I'm gonna see if I can get a code reader and see if I get any troublecodes. If anyone has any ideas on what I can do, The help would be greatly appreciated.

In my experience i would lean towards the TPS the throttle position sensor simply because the fact that you have to spray starting fluid in it to get it started i once bought a new TPS for my jeep and with the new TPS i needed to spray starting fluid to start it after changing the TPS again i no longer had that problem