j12784

Cranks but doesn't start. The mechanic did something tricky with the fuel pump relay, because it's flooding, and got it to start.

I changed the distributor, CPS, welded a crack in the exhaust manifold before the o2 sensor.

I didn't want to try and start it by doing something tricky with a relay. that doesn't seem like sound mechanics to me. I just want to start the damn thing.

I did a compression test and its getting 120 across the board. I think some people said 150 was good for these? I figure if its low on all cylinders its most likely not a head gasket issue, and when the other mechanic got it running it ran just fine untill i let it idle for a 10-12 minutes at which point it overheated a little and started to idle very rough, and then turned itself off.

that's all i can think of right now.

hope you all can help me.

DFlintstone

Really I should know by now after bumping around here since 2011.....Is your MAP sensor still up on the firewall, maybe with a green wiring connector? (might be 94 it moved to the throttle body) If so there is a brittle little tube from it, down and back to the engine side of the throttle body. Any little crack or blockage in that line will make it run pig rich. I just repaired mine with vacuum line. At Crusier54.com he has a bulletproof modification for that well known stinker..

dave1123

I think on my 97 ZJ, it was mounted on the manifold but still had a short piece of hose connecting it to the base of the throttle body. My 2000 is mounted directly on the side of the throttle body.

Jeepwalker

Is there a 'Spark' at the plugs?

Your compression could be low if you tested it in the process of trying to start it, and the cylinder walls are washed with fuel. Even if they were 120 across the board ...which is low (under a 'proper' compression test), it should still start and run.

DFlintstone

Yes...for sure on Cherokee there is just a little elbow under the MAP on the TB after 96-97. Thinking the firewall MAP move might be a rare change during OBD I. Cruiser likely knows but is probably getting tired of correcting me! In any case it's easy enough for "J" to take a look and see.

j12784

j12784

DFlintstone

I'll back out now and defer to others to help. Your OBD one, you can search the "key trick" and it will display codes for you. (codes are listed in the "sticky" section) Know that it's the MAP that "roughs out" a fuel trim, (injector pulse width), using manifold vacuum, normally from the TB, should allow it to run. (it's OK to tap manifold vacuum elsewhere) After it warms and switches from computer defaults in "open loop", the "upstream" O2 sensor (s') then dial it in better, (in "closed loop") If it's for sure rich, may well be something with the wires or connections, or even the map it's self. Looking at sensor grounds at Crusier54.com might prove helpful. None can give correct info to the puter if the grounds are bad.

A no start with spark, flooded, is almost certainly something to do with the MAP I'd guess.

j12784

j12784

j12784

also i tested the spark, and its very good. also keep in mind the mechanic got it started, i drove it 5 minutes, then let it idle for 10 minutes before it started to idle very rough then die. while it was running in ran VERY smooth, but was a bit squishy somehow on the gas pedal before it would get up to 1.5k rpms, and then it would respond normally.

j12784

also the guy working on it before me did something to wipe the codes. so the key trick to get any sort of codes out of it does not seem to work. i did however test the MAP, and any electrical component I could watch a you tube video about. everything seems to check out just fine. i also tested a different coil that I got from the yard, but the plug was different so i had to take the leads out of the plug and attach it to the new coil, which came out of a 4.0L to no avail. didn't do anything different.

I also ran a ground from my temp sensor to rule that out. no different upon cranking with a ground lead from the battery to the temp sensor.

Jeepwalker

Well, you have spark ....now do you have fuel? When you turn the key to the "On" position (but not cranking), can you hear the fuel pump hum for like 3 seconds then shut off?

The only thing I can think of that would keep it from starting is the CPS (if you got a 'bad one'), or no-fuel situation. I would think a bad CPS would shut down the spark ...but I'm not 100% on ther. Is there a shut-off or 'reset' for the fuel pump back by the spare tire? Might be time to start checking wires and that relay.

I'm assuming by your original description of the problem, you had changed the distributor and CPS **before** the mechanic got it running, right? So the engine timing is correct (??). I would pull the codes if you haven't already. The way you do that is by turning the key on/off a number of times in a certain sequence, then watch the Check Engine light blink (counting the blinks). Just google how to do it. It's been a while since I've done it. After you pull the codes, you 'might' remove both battery connections and hold the cables together for 20 seconds (to drain the ECM capacitors), then reconnect the battery cables and try starting it ...just to see what happens. Double-check all the wiring connectors in case one has pulled slightly apart, including the CPS in case it also isn't 100% in place.

j12784

i disconnected the fuel at the rail, and a lot came out. no plugs in the filter, and the pump seems to run really well.

correct. the reason i took it to the mechanic is because I had suspicions of installing the distributor wrong, and i was right. so he put the motor top dead center, and reinstalled the dist and then doing his fuel pump relay trick he got it started after cranking the poop out of it. basically killing the battery.

the fact that it ran and it ran well for a short while makes me feel like the cps is working and installed correctly.

j12784

also the guy i bought it from said he installed a new fuel pump. i have no way to verify this, but he seems like a strait shooter, and has offered a lot of help since i bought the jeep.