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Comanche with 1997 4.0 bogging issues


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Have a 1988 comanche with a 97 4.0

Starts and idles fine after 5 minutes of driving it starts to bogg down and a small backfire sound from intake I'm assuming. Only code I have is 42. 

open or shorted condition detected in the auto shutdown relay circuit. An open condition detected in the ASD relay output circuit. An open or shorted condition detected in the fuel pump relay control circuit. An open circuit between PCM and fuel gauge sending unit. Circuit shorted to voltage between PCM and fuel gauge sending unit. No movement of fuel level sender detected. 

but I'm not sure if this is relevant due to the mismatch between the newer motor and the stock mj fuel pump. Gauge reads backwards. 

new plugs, wires, IAC, upstream 02. 

been at a loss for a couple  weeks now. No other codes except battery temperature due to I don't have  one. 

please help

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On acceleration, doesn't matter if on hill or not. Before it starts I have zero issues with speed. Once it begins I gotta limp home. I can feather peddle to get past the bogging but it comes right back. I drove to my buddies house other day and it did it on way there didnt think I would make it but on way home it didnt sputter once but I was light on peddle but 99% of time its doing this

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35 minutes ago, Dzimm said:

Does it bog during acceleration and going up hill?  How fast can you go?  

 

Possibly a clogged cat

 

8 minutes ago, Dzimm said:

How old is the cat converter?  

Not sure. Have only owned the comanche for a couple of months.  The flowmaster sounded like it had something in it before I cut it off 

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So the exhaust is hacked up currently?  I'd go take the cat off and see what it does.  Or punch a hole in the front of it with a screwdriver.  This is assuming you have a welder or way to fix it after the test because it will be loud. 

 

It does sound like that's a false code with your fuel pump wiring, but check your spark plugs for signs of flooding and check fuel rail pressure just to know for sure.

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2 minutes ago, Dzimm said:

So the exhaust is hacked up currently?  I'd go take the cat off and see what it does.  Or punch a hole in the front of it with a screwdriver.  This is assuming you have a welder or way to fix it after the test because it will be loud. 

 

It does sound like that's a false code with your fuel pump wiring, but check your spark plugs for signs of flooding and check fuel rail pressure just to know for sure.

I pieced a stock muffler on temporary . Its tagged historical so I guess I could just remove it "temporary"

I had a high fuel pressure issue. They put the 97 motor in which has no return line and no regulator on the rail. I replaced it Saturday  with used products with the return line and rail regulator and havnt been able to test the pressure yet but before the swap it was at a steady 87psi. So unless this regulator is bad it should have dropped. If the fuel pressure  is the issue would the ecu default function normally  then once it allows the 02 sensor to work just mess it all up?

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2 minutes ago, Eric sicca said:

I pieced a stock muffler on temporary . Its tagged historical so I guess I could just remove it "temporary"

I had a high fuel pressure issue. They put the 97 motor in which has no return line and no regulator on the rail. I replaced it Saturday  with used products with the return line and rail regulator and havnt been able to test the pressure yet but before the swap it was at a steady 87psi. So unless this regulator is bad it should have dropped. If the fuel pressure  is the issue would the ecu default function normally  then once it allows the 02 sensor to work just mess it all up?

You put a vacuum line on the fuel regulator correct?  It should work just fine with the fuel regulator and the MJ pump.  Should never have been setup returnless with the MJ pump.  

 

Did a PO or someone other than you build this truck?

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6 minutes ago, Dzimm said:

You put a vacuum line on the fuel regulator correct?  It should work just fine with the fuel regulator and the MJ pump.  Should never have been setup returnless with the MJ pump.  

 

Did a PO or someone other than you build this truck?

The PO did and yes I hooked up the vacum to regulator. If regulator was bad it could be flooding I suppose but what are the odds of the same exact issues. Only thing I did not replace was the injectors only because they where direct fit with the the new rail and where the same kind from the 95. I got the clips with pig tails when I got the new system expecting they would be different on this but they were the same one hole with same clips

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Just now, Eric sicca said:

The PO did and yes I hooked up the vacum to regulator. If regulator was bad it could be flooding I suppose but what are the odds of the same exact issues. Only thing I did not replace was the injectors only because they where direct fit with the the new rail and where the same kind from the 95. I got the clips with pig tails when I got the new system expecting they would be different on this but they were the same one hole with same clips

Unless they are wrong injectors but fit the 91 thru 95 clips

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The injectors are standard size, different flow rates.  Here's info and part numbers I pulled from another forum.

 

The following is a list of the injectors used on the 4.0L since 1987 along with their rated static flow:
Model Year Part Number Color Fuel Pressure Static Flow 

87-1990 53003956 Black 39psi 18.6lb/hr 

91-1993 33007127 Brown 39psi 21.0lb/hr 

94-1995 53030343 Tan 39psi 21.0lb/hr 

96-1999 53030778 Grey 49psi 23.2lb/hr 

99-06 04854181 Blue Tip 49psi 22.5lb/hr 

The injector flow rate varies as the square root of the pressure drop across the injector. The stock '91-'95 4.0 injectors are rated at 22lb/hr @ 43psi fuel pressure, so at 39psi they flow ( sq. rt.(39/43) x 22.0 = 21.0 ). 

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8 minutes ago, Dzimm said:

The injectors are standard size, different flow rates.  Here's info and part numbers I pulled from another forum.

 

The following is a list of the injectors used on the 4.0L since 1987 along with their rated static flow:
Model Year Part Number Color Fuel Pressure Static Flow 1987-1990 53003956 Black 39psi 18.6lb/hr 1991-1993 33007127 Brown 39psi 21.0lb/hr 1994-1995 53030343 Tan 39psi 21.0lb/hr 1996-1999 53030778 Grey 49psi 23.2lb/hr 1999-2006 04854181 Blue Tip 49psi 22.5lb/hr The injector flow rate varies as the square root of the pressure drop across the injector. The stock '91-'95 4.0 injectors are rated at 22lb/hr @ 43psi fuel pressure, so at 39psi they flow ( sq. rt.(39/43) x 22.0 = 21.0 ). 

So they are grey, the ones I got with the rail off the 95 where orange. The 97 motor requires 50 psi I believe. Just been a royal pain in my butt

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1 minute ago, Eric sicca said:

So they are grey, the ones I got with the rail off the 95 where orange. The 97 motor requires 50 psi I believe. Just been a royal pain in my butt

Yeah fixing other people's work is a pain.  I cleaned up the list so it makes more sense, was clustered up before. 

 

You'll want these injectors:

96-1999 53030778 Grey 49psi 23.2lb/hr

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2 minutes ago, Dzimm said:

Yeah fixing other people's work is a pain.  I cleaned up the list so it makes more sense, was clustered up before. 

 

You'll want these injectors:

96-1999 53030778 Grey 49psi 23.2lb/hr

Yeah that's what's in now with the earlier 1991 thru 95 rail an regulator.

Unless the regulator is shot and allowing the same high psi through I think it's another issue all together 

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6 minutes ago, Dzimm said:

You need to test the fuel rail pressure. 

 

The stock 91-95 regulator should hold the rail at 39psi.  You would need an adjustable regulator to get 49psi.  

Yes or a dodge caravan regulator which would bump it up 10 more. Just with the same exact issue as before the swap makes me leery it's not the fuel pressure unless it's still at 87 psi after the swap. Would a bad regulator keep it up that high?

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4 minutes ago, Eric sicca said:

Yes or a dodge caravan regulator which would bump it up 10 more. Just with the same exact issue as before the swap makes me leery it's not the fuel pressure unless it's still at 87 psi after the swap. Would a bad regulator keep it up that high?

Potentially but it needs sorted regardless.  Test the rail pressure to see exactly where you are at and then adjust from there.  If it turns out not to be there then move on to the cat. 

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4 hours ago, Dzimm said:

Potentially but it needs sorted regardless.  Test the rail pressure to see exactly where you are at and then adjust from there.  If it turns out not to be there then move on to the cat. 

So I checked the pressure  it's at 36 which I low but better then 87 which it was. But at further inspection I found a 2.5 inch piece of the converter in the old flow master.....

20190805_153701.jpg

20190805_153244.jpg

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So you definitely need to get that cat replaced.

 

If it starves of fuel it will fall on its face. Given its acting exactly as it did when you had too much pressure I'm guessing your main issue is the cat but the fuel is definitely not helping.  

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9 minutes ago, Dzimm said:

So you definitely need to get that cat replaced.

 

If it starves of fuel it will fall on its face. Given its acting exactly as it did when you had too much pressure I'm guessing your main issue is the cat but the fuel is definitely not helping.  

Definitely running better and didnt bog down but it did backfire alot and stulled and died once from a start on a hill.

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  • 1 month later...
2 minutes ago, Vandenborg1 said:

So I have this same problem does worse on acceleration and on a hill with my 88 comanche with the cat removed any ideas

Check your fuel pressure of its lower then the requirements pull the fuel assembly and check the hose that's inside tje tank the connects to the pump. It's a few inches long. If that seems fine replace the pump. Also if you havnt changed the fuel filter that's on the frame I'd start there

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