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Turnover, No start


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So before I anticipated leaving for school, I went into the jeep and tried to start it. It turns over but won't start. This is the first time this has occured on this motor. I have the Renix 4.0 with 212k and have no knowledge how many miles are on the fuel pump. I couldn't hear the humming noise when priming the system, so I'm wondering if it's the pump or a relay, resistor, or CPS. I don't remember for sure but I thought the PO told me he's replaced the CPS. Do they just spontaneously go bad? What do I need to check first before buying a $100 fuel pump? Please help, I need to drive it ASAP to college and not miss anymore school days because of the heep. Thanks in advance!

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First, check to see if it is getting fuel.  Lots of write ups on how to do this.  One simple way is try cranking the engine; turn it off; press the fuel rail pressure release valve.'

 

WEAR GLASSES! HAVE A RAG TO COVER THE VALVE.  GAS WILL SPRAY!

 

This will tell you if fuel is getting to the rail.

 

Next, test for spark.  Pull one of the spark plugs.  Hold it close to a ground.  Have a partner crank the engine.  See if it sparks.

 

No Fuel: trace lines back to tank looking for blockage.  Replace fuel filer? relatively inexpensive.  Test wires to fuel pump.

 

Before Cruiser says it, check out his tips for Renix engines.  www.cruiser54.com

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UPDATE: We have fuel pressure in the rail and I hear the fuel pump priming, had the electric fan running full time, so I temporarily disconnected so I could hear it and I can. The problem is no spark. I used a spark tester and checked one of the spark plug wires and the one coming off the coil pack to the distributor and nothing. Here's the catch, the CPS looks like it was recently replaced, so I'm not positive it's that. What do you think? Also there's seems to be some screeching noises coming from the engine compartment as if something is worn. Battery is charged but haven't tested the leads. Please help! Needs to be driveable next week if possible. Thanks.

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UPDATE: We have fuel pressure in the rail and I hear the fuel pump priming, had the electric fan running full time, so I temporarily disconnected so I could hear it and I can. The problem is no spark. I used a spark tester and checked one of the spark plug wires and the one coming off the coil pack to the distributor and nothing. Here's the catch, the CPS looks like it was recently replaced, so I'm not positive it's that. What do you think? Also there's seems to be some screeching noises coming from the engine compartment as if something is worn. Battery is charged but haven't tested the leads. Please help! Needs to be driveable next week if possible. Thanks.

Test the CPS

 

Tip7 at www.cruiser54.com

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a low power cps or bad cps will not allow the dizzy to spark, and will not allow the EFI to work. CPS is what tells the engine at what part of crank it is at to inject fuel and to control timing advance and retard. The ecu needs to get a signal constant so both dizzy and efi to work. If the magnet on cps is full of gunk, shavings or what ever, it will cause a low voltage a no start and some times stalls during running. Also make sure the surface is clean and the bolt is mounted right.  above Cruiser has a tip on number 7 I think that you drill out hold 3/8 to get a better fit against the bellhousing.

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  • 2 weeks later...

UPDATE: I have replaced the CPS with a MOPAR one, not that BME bull$#!&, and still not starting. I haven't tested the outcome voltage yet, but I'm thinking already it's something else. Besides the C101, I'm thinking it could be the ICM. Does this sound like the next thing to check/or even just replace? I took the coil out and tested it before and it tested fine and the terminals look good, but maybe it spontaneously wore out and quit working. If I do buy one, you bet it will be MOPAR! 

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I forgot to mention that, when I did the engine swap to this motor, it had an issue of shutting off. Long story short, I cut the b-latch relay wire or whatever that yellow wire that goes to the ICM and then it would turn off. Is this wire that is cut a possible issue? I don't think so since it has ran fine without that wire connected.

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What was I supposed to do? I put in a new ignition switch and it still wouldn't turn off until we cut the yellow wire. I will say some of the wiring is butchered from the PO, but I've been fixing it with waterproof butt connectors since I don't own a soldering gun. That is really the only mod done to the wiring in order for it to shut off. I am tedious when working on the jeep and I have to be as I am going to school as a CNC Machinist. Please, I'm asking for help, not criticism. Thanks

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I've successfully soldered with butane lighters. Regular cigarette lighters leave too much soot residue and aren't nice to fingers, but can be used in a pinch.

 

If you put that yellow wire back together, what happens? Twisting the wires together would be enough to determine if it's the problem. What made you decide to cut the wire in the first place? Anything else you've done? Probably wouldn't hurt to check all the butt connectors. If they're not solidly crimped, sometimes they like to shake apart.

Do you have an electrical manual? There's one that's been floating around on here recently.

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I've had hooked it back up, and you can hear the relay work. It still doesn't start, so I don't think it's a problem. I'm thinking the ICM. I've been told it's rare for them to go out, but it's the last thing I can think of besides redoing/cleaning the C101.

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I've refreshed the grounds behind the oil dipstick. I've tested the old CPS, and it was bad, so I got a new one, but I haven't tested it yet, due to a dead battery now. I've done the headlight harness upgrade, new vacuum harness; both sides.

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What was I supposed to do? I put in a new ignition switch and it still wouldn't turn off until we cut the yellow wire. I will say some of the wiring is butchered from the PO, but I've been fixing it with waterproof butt connectors since I don't own a soldering gun. That is really the only mod done to the wiring in order for it to shut off. I am tedious when working on the jeep and I have to be as I am going to school as a CNC Machinist. Please, I'm asking for help, not criticism. Thanks

I never criticized anything. Just stated facts. 

 

If you're more comfortable without my input, that can be arranged. 

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I want all the input I can get. I'm really not interested in getting into a piss match with anyone on here. I've purchased a new ICM that I will pickup tomorrow and will install it tomorrow. I can also inspect in the connectors since,as mentioned by you cruiser, there isn't really a good right up for testing it. I plan on deleting the c101 this weekend as well. If that doesn't work, I will clean the ECU connectors. Sound good or am I missing something obvious?

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UPDATE: So I put in the new ICM and it fires! This is until I turn it off, so I can put my e fan wire back on, so I can let it charge. It's not starting again, but cranking over. Do you think I have a faulty ICM? or There's gunk on the CPS? I'm running out of ideas. Please help!

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Just put a new cap and rotor on. Runs great when started, but when you turn it off and try to start it again, it doesn't want to. What do you think it is? I'm thinking when I replaced the CPS, there may have been some gunk on it, I don't really remember, so it's getting a low voltage. Anyone agree before I tear it apart again? 

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So what you're saying is it'll fire up and run great if it's been sitting, but if you shut it off it won't start up again?

 

Am old Chevy I was messing with did that sometimes. I dicked around with it a bunch, my grandpa (retired mechanic) did as well. We'd replace one thing, then another and another, each one seemingly fixing the problem for a couple days, or weeks, but eventually it would just randomly lose spark. Eventually we gave up and took it to a mechanic. He kinda went through the same process, and eventually just went ahead and replaced the whole distributor. When he did that, he noticed that one of the coil wires had slowly rubbed/burned through, and was shorting out. Sometimes when messing with it, we'd push it away from contact for a bit and it would run great, until the wire wiggled itself back.

 

Beyond that anecdote, I don't have much else for you. Unfortunately I'm pretty unfamiliar with the Renjx system. When I get home tomorrow I'll try digging up that electrical manual for you.

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