Renix Cranks But Won't Start, Have Spark, Fuel And Compression
Working on my '88 4.0 aw4 4x4.Two weeks ago I went to a store and when I came out, the heep would crank but nothing else.
Fast forward to now, I have replaced or adjusted: Distributor/cap/rotor/wires are new, the tab was removed and the dizzy has been indexed to TDC (confirmed compression stroke by removing valve cover and checking rockers) and the rotor is at the 5 o'clock position with the dizzy adjusted to be at the trailing edge of the rotor tip. CPS was replaced (low voltage reading while cranking spurred the replacement) TPS was adjusted a few days before it stopped working, should I recheck it? Grounds at dipstick have been cleaned and the head to firewall ground replaced. Coil was replaced with junkyard unit because mine had a crack. ICM contacts were cleaned C103 eliminated, wires joined with non-insulated crimp connectors and heat shrink. Fuel pump and filter are brand new but I had to reuse the old fuel strainer as the replacement wouldn't fit in my tank. TB and IAC were cleaned when the TPS was adjusted. Vacuum lines are all intact but the TB to map line was replaced by the PO with clear tubing. I have spark to the plugs. I have fuel in the rail. What am I missing? She cranks strong but won't fire, only rarely will it grumble a little bit. I'm pulling my hair out at this point. Please help. |
Originally Posted by GreanBeastXJ
(Post 3532747)
Working on my '88 4.0 aw4 4x4.Two weeks ago I went to a store and when I came out, the heep would crank but nothing else.
Fast forward to now, I have replaced or adjusted: Distributor/cap/rotor/wires are new, the tab was removed and the dizzy has been indexed to TDC (confirmed compression stroke by removing valve cover and checking rockers) and the rotor is at the 5 o'clock position with the dizzy adjusted to be at the trailing edge of the rotor tip. CPS was replaced (low voltage reading while cranking spurred the replacement) TPS was adjusted a few days before it stopped working, should I recheck it? Grounds at dipstick have been cleaned and the head to firewall ground replaced. Coil was replaced with junkyard unit because mine had a crack. ICM contacts were cleaned C103 eliminated, wires joined with non-insulated crimp connectors and heat shrink. Fuel pump and filter are brand new but I had to reuse the old fuel strainer as the replacement wouldn't fit in my tank. TB and IAC were cleaned when the TPS was adjusted. Vacuum lines are all intact but the TB to map line was replaced by the PO with clear tubing. I have spark to the plugs. I have fuel in the rail. What am I missing? She cranks strong but won't fire, only rarely will it grumble a little bit. I'm pulling my hair out at this point. Please help. |
Even with some new fuel pump components, gotta verify fuel delivery with a fuel pressure gauge. For your vintage, you need 31 psi to fire the engine. Or introduce a little bit of raw fuel into the intake. If it starts and runs for a few seconds this "old school" way, you have identified a fuel delivery problem.
Test the cam sensor (synch sensor) located inside your distributor. |
As stated above, fuel PRESSURE needs to be verified.
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Originally Posted by Idunno
(Post 3532791)
Reconfirm compression stroke by removing all plugs and putting your finger on #1 plug port to actually feel compression while rolling engine by hand. Once there, where is the distributor button pointing? If you have spark and fuel pressure on the rail then the only problem I can see is an incorrectly indexed distributor.
If I spray ether into the TB the jeep will rumble and fire like it wants to start but won't. When I say I have fuel at the rail, I mean there is fuel there when I press the valve on the rail. It only dribbles out though, it doesn't seem like 31PSI. I bought a cheap harbor freight fuel pressure gauge but it was garbage and leaked out of the box. I currently don't have the funds to rent one from Oreillys for $135. I know it's a fuel system issue now. Fuel pump relay is clicking. fuel pump pressurises with the key on. I've read that these pumps often are victims of crib death. Could that be the case even though I can hear it start? Fuel lines all seemed intact when I replaced the pump and filter. Ballast resistor contacts are clean, what should the resistance be? At this point I am inclined to put the old pump (Bosch, was working but was suspect) back in and see what happens. I think I will tackle tip #29 while I am down there. Also in post #1 I meant the c101, not the c103. Thanks for the input guys and thanks Cruiser for the Renix site. It's a life saver. |
Good plan.
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Old pump went in today but I lost the fuel strainer in the tank while installing it. oops! Any way she REALLY want to run now. It will fire like it's gonna take off on it's own but it just won't stay running. My best guess is the timing is slightly off.
Thoughts? |
Originally Posted by GreanBeastXJ
(Post 3533542)
Old pump went in today but I lost the fuel strainer in the tank while installing it. oops! Any way she REALLY want to run now. It will fire like it's gonna take off on it's own but it just won't stay running. My best guess is the timing is slightly off.
Thoughts? DISTRIBUTOR INDEXINGOCTOBER 30, 2015 SALAD 27 COMMENTS EDIThttps://i1.wp.com/cruiser54.com/wp-c...size=300%2C175https://i1.wp.com/cruiser54.com/wp-c...size=300%2C169
Distributor indexing explained For clarification though, that’s not a cam sensor inside the Renix dizzy. It’s there to fire the injectors sequentially with the firing order. You’ll never notice if it went bad because the ECU will try to “guess” where it is and does a heck of a job at it. As for the “timing”, it is controlled by the ECU. Ever notice how wide the tip of the rotor is? Try and wrap your head around this: When the ECU yells “Fire” to the ignition control module, where is the rotor in relationship to the dizzy terminal? Not to the terminal yet? Past the terminal too far? What happens to the spark/secondary ignition strength when it has to jump the Grand Canyon in comparison to shooting from a rotor tip? Use Tip 12 first to guarantee you’re on #1 TDC. Revised 11-19-16 |
Also, make sure your fuel pump ballast resistor if it's starting, and then dying in a few seconds.
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Indexing was off. Heep running now. Thanks for the help!
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Originally Posted by GreanBeastXJ
(Post 3534059)
Indexing was off. Heep running now. Thanks for the help!
Cool!!!!! |
Ditto! In the link in my sig there is a pic of the inside if the tank BTW.
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