OVERfueling problem

crown14

crown14

Well-known member
May 11, 2006
6,288
4
Clayton, NC
1995 model, 3.9L- actually not a RRC but a auto Disco. 14CUX discussion seems more appropriate in this section!

Truck sat for a little while, upon initial check-over discovered MISSING fuel cap, MAF, and dead fuel pump. Replaced fuel pump, cleaned out gas tank, installed a MAF and fired up. Would start and run long enough to move around, couldnt run much longer due to stolen converters... :banghead:

Pulled it in to rig up some makeshift exhaust and it woudnt start back up after. Pulled valve core from test port on fuel rail, connected a hose and using key to cycle fuel pump filled a bottle with fuel. In the fuel discovered some water and several small chunks of "dirt", magnet test proved them to be rust so the fuel rail and injectors were replaced with known good ones. Cleaned out fuel lines, replaced filter, cleaned fuel tank again, filled with new fuel and checked fuel pressure (good)... truck still not starting. Spark present at plug, nice and strong, but tried another known good module/coil/cap/rotor/wires and new plugs for good measure- no luck. Fuel smell in exhaust, disconnect fuel pump connector and it starts right up!! Runs a few seconds, begins to stumble due to lack of fuel. Reconnect fuel pump and it will stay running...

My question is why in the hell do I have to disconnect the fuel pump to start the engine??? Injectors were correct ones, fuel pressure regulator is the correct one, but it appears as if the pulsewidth is off the chart? Have not got a noid lite or a scope here, doing this the old fashioned way.

Have ohmed out the fuel temp and coolant temp sensors and am getting normal values at the sensor and probing the ECM connector. By the way the O2 sensors are missing from the truck also, however until the truck is warmed up computer should be in open loop and basically ignoring them.
 
slowNstdy

slowNstdy

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Nov 28, 2005
408
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Mckinney, Tx
kk88rrc said:
I would have said coolant temp sensor but you said checks out fine. Maybe try starting it with it unplugged. Did you test it cold & hot?
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X2 i believe its refered to as a coolant thermistor.
 
crown14

crown14

Well-known member
May 11, 2006
6,288
4
Clayton, NC
D Chapman said:
Sounds like it's flooded..??? Maybe a leaking injector(s)?
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Yes its flooding out, which I was very surprised to discover. I suppose that a pissing injector(s) is a possibility, but the injectors came off a truck that ran fine and I would expect that one leaking injector wouldnt keep the truck from starting and multiple ones would bleed off fuel pressure almost immediately which is not the case.

sven said:
New fuel pump wired backwards? Is it even possible...I dunno
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Maybe its just depressed. Ill buy it a hallmark card and some D2 cupholders.

kk88rrc said:
I would have said coolant temp sensor but you said checks out fine. Maybe try starting it with it unplugged. Did you test it cold & hot?
Click to expand...

Unplugging the pump is the only way to get it started, then to keep it running I have to plug it back in. Not sure what you mean by cold and hot, its in my shop now, approx. 64 degrees Fahrenheit, resistance was around 2400 ohms IIRC. Runnning the truck to operating temp with no exhaust (was cut just aft of the O2 bungs) and no O2 sensors isn't really an option.
 
K

kk88rrc

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Mar 26, 2007
1,187
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Portland Maine
www.kevinkeithphoto.com
crown14 said:
Unplugging the pump is the only way to get it started, then to keep it running I have to plug it back in. Not sure what you mean by cold and hot, its in my shop now, approx. 64 degrees Fahrenheit, resistance was around 2400 ohms IIRC. Runnning the truck to operating temp with no exhaust (was cut just aft of the O2 bungs) and no O2 sensors isn't really an option.
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I was curious if you tested the CTS when the truck was at temp but I see that's not an option. I meant unplug the CTS to see if it starts. Is it possible to heat the CTS to make the ECU think it is warm therefore leaning the fuel out somewhat. Just thoughts.
 
crown14

crown14

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May 11, 2006
6,288
4
Clayton, NC
ptschram said:
Pressure regulator leaking into plenum?

Sounds like it's flooded at start. Does fuel pressure decline at all when key turned off?
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You mean leaking through the vac. diaphragm on the regulator, up the hose and pooling fuel in the bottom of the ram manifold? Interesting thought, I will have to look into that. Probably wont have a chance to look at it again for a couple days, will re-test (and record) fuel pressures again as well.
 
ptschram

ptschram

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Sep 27, 2004
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In the shop doing the Lord's work one broken Rover
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crown14 said:
You mean leaking through the vac. diaphragm on the regulator, up the hose and pooling fuel in the bottom of the ram manifold? Interesting thought, I will have to look into that. Probably wont have a chance to look at it again for a couple days, will re-test (and record) fuel pressures again as well.
Click to expand...

It's rare, but it sometimes happens.
 
crown14

crown14

Well-known member
May 11, 2006
6,288
4
Clayton, NC
OK - hesitant to give an update for fear it begins to act up again.... BUT for now its running. Heres what happened:

It got to the point where even plugging/unplugging the fuel pump wasnt enough to get it started, so I took PT's suggestion and swapped in the known good ECU from one of my 95 LWB trucks- it again sounded like it wanted to start but couldnt quite get there and then cleared up and started- and idled- with the fuel pump still hooked up. I "made up" an exhaust for the truck and afterwards it started up and idled. Installed a muffler and afterwards, guess what, it still starts and idles. Changed the oil and, you guessed it still starts and runs. I even drove it around a little and its running great aside from hunting a base idle mixture once warmed up which I figure isnt unusual considering the absence of o2 sensors. Later I got bold and swapped the original ECU back in and it started right up and idles fine... so it seems all is good for now.

Next step is convincing the truck that its not an 02 sensor version...
 
ptschram

ptschram

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Sep 27, 2004
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In the shop doing the Lord's work one broken Rover
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While I'm disappointed that we don't know why it is running, at least it's running.

Wouldn't you know, I'm now in the same boat with one of my '93s that won't run. Had a buzzing ignition load relay, swapped a relay (from an engine on a rolling chassis outside next to the truck, LOL). Cleaned up grounds, got fuel to the rail, have spark, but cannot get the injectors to open.

IT RAN WHEN WE PARKED IT GRRR!
 
crown14

crown14

Well-known member
May 11, 2006
6,288
4
Clayton, NC
sven said:
You mean delete the o2s all together? Why you wanna do that?
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Yeah that was optimistic kidding, it would be nice to do away with them instead of spending the $200 on new ones. Plus my new Y-pipe hasn't got I went to pull the ones of one of my LWB trucks and found one cut off at the sensor and a bolt in place of the other one. :banghead:
 
crown14

crown14

Well-known member
May 11, 2006
6,288
4
Clayton, NC
Thanks for the tip PT

I am also researching the possibility of a cheaper alternative, since I will be having to add O2 bungs to the pipes anyway... and the design of the ESR225 means I will have to lengthen the wiring to the sensors anyhow.
 
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