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Renix backfiring/popping
1988 Renix Cherokee
List of things already done: Throttle body cleaned IAC Cleaned IAT Cleaned TPS adjusted to spec Butterfly Adjusted to spec CTS Replaced CPS Replaced C101 Connector Cleaned Grounds refreshed (.5 Ohms pobing B on TPS) New Plugs Gapped to spec New Rotor in distributor No Vacuum leaks It's like the Jeep is out of time but from what I understand these are automatically timed. When you floor it, it doesn't have full power, it will bog and when revved in neutral it will backfire and occasionally pop.. I've been dealing with this thing for 4 weeks... Someone has to have some info. |
Job #1 is to verify fuel pressure. I didn't see that on your list. Backfiring is often due to an imbalance in fuel/air ratio. Verifying fuel pressure is one of the first things a technician would check if you took it to a shop. Must be done with a fuel pressure gauge which can be rented inexpensively from many parts stores; call around for availability. There are other possibilities to be sure, but gotta rule fuel pressure in or out before moving on......
For an 88, you should have 31 psi at idle. Then disconnect the vacuum line leading to the fuel pressure regulator and the pressure should jump to approximately 39 psi. Be darn sure that the vacuum line is not wet with raw fuel, which would indicate a ruptured fuel pressure regulator. Good luck and keep us updated! |
Originally Posted by tjwalker
(Post 2717044)
Job #1 is to verify fuel pressure. I didn't see that on your list. Backfiring is often due to an imbalance in fuel/air ratio. Verifying fuel pressure is one of the first things a technician would check if you took it to a shop. Must be done with a fuel pressure gauge which can be rented inexpensively from many parts stores; call around for availability. There are other possibilities to be sure, but gotta rule fuel pressure in or out before moving on
...... For an 88, you should have 31 psi at idle. Then disconnect the vacuum line leading to the fuel pressure regulator and the pressure should jump to approximately 39 psi. Be darn sure that the vacuum line is not wet with raw fuel, which would indicate a ruptured fuel pressure regulator. Good luck and keep us updated! I think this issue has something to do with my starting issue as well which is when its cold it won't start. |
Question. How can you have 31 at idle with the engine off? With just the key turned on, the pressure should be closer to 39 and it should hold after you turn the key off. If you start it and let it idle, pressure should be about 31. Pull the vacuum line to the regulator and it should jump up to around 39. You might want to double check to be sure you're ok.
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Have you checked the map sensor line for cracks yet ? Also confirmation of vacuum to it when idleing .
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Originally Posted by PDEM87
(Post 2717103)
Question. How can you have 31 at idle with the engine off? With just the key turned on, the pressure should be closer to 39 and it should hold after you turn the key off. If you start it and let it idle, pressure should be about 31. Pull the vacuum line to the regulator and it should jump up to around 39. You might want to double check to be sure you're ok.
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By the way, I must commend you on your perservierance with learning the Renix system. I too am on my first Renix and they are not easy. Had a 96 xj before the 87 I have now. Very different!
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Originally Posted by cherokeeyed
(Post 2717015)
1988 Renix Cherokee
List of things already done: Throttle body cleaned IAC Cleaned IAT Cleaned TPS adjusted to spec Butterfly Adjusted to spec CTS Replaced CPS Replaced C101 Connector Cleaned Grounds refreshed (.5 Ohms pobing B on TPS) New Plugs Gapped to spec New Rotor in distributor No Vacuum leaks It's like the Jeep is out of time but from what I understand these are automatically timed. When you floor it, it doesn't have full power, it will bog and when revved in neutral it will backfire and occasionally pop.. I've been dealing with this thing for 4 weeks... Someone has to have some info. No plug wires? |
1 Attachment(s)
With the engine running, get a voltage reading on each terminal of the fuel pump ballast resistor.
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Hey guys I know its a little off subject but that ballast resistor... what's the cons and pros?
And why some people just bypass them instead of buying a new one? |
Originally Posted by Batman33165
(Post 2782543)
Hey guys I know its a little off subject but that ballast resistor... what's the cons and pros?
And why some people just bypass them instead of buying a new one? Supplies 12 volts to the pump on cranking and drops the voltage to about 10 when running. Bypass it. Pump too loud? Hook it back up. |
Ok, thanks cruiser...
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