Walbro Not Working . . .
02-16-2006, 11:16 AM
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Walbro Not Working . . .
I just installed a Walbro set-up on my son's 04.5 CTD w/ 145k after diagnosing 0 psi at idle. It also smoked and had low power.
Set-up went well including 1/4" by-pass line at CP3. I used the OEM 2-wire electrical wire to power the Walbro pump mounted on frame. I also installed a FP gauge at top of filter. Initial FP was 15-20 psi at idle. Took it out for a road test . . . still smoked w/low power!
Well, I thought I just had other problems. I turned to the turbo/intake system to look for a air leak. I scanned the ECM for codes - only codes were low FP from before installing Walbro. I cleared the codes and tried again - no codes. I took it in to DC - they said I had a low FP code and that it was my problem since I had messed with the system!
My question is . . . Is there enough power to run this pump? Did I blow it by installing 1/4" by-pass line? DC got no power at the pump, so is the ECM rejecting the pump based on a different load? Can I wire the pump straight to the an aftermarket relay and switched B+?
Set-up went well including 1/4" by-pass line at CP3. I used the OEM 2-wire electrical wire to power the Walbro pump mounted on frame. I also installed a FP gauge at top of filter. Initial FP was 15-20 psi at idle. Took it out for a road test . . . still smoked w/low power!
Well, I thought I just had other problems. I turned to the turbo/intake system to look for a air leak. I scanned the ECM for codes - only codes were low FP from before installing Walbro. I cleared the codes and tried again - no codes. I took it in to DC - they said I had a low FP code and that it was my problem since I had messed with the system!
My question is . . . Is there enough power to run this pump? Did I blow it by installing 1/4" by-pass line? DC got no power at the pump, so is the ECM rejecting the pump based on a different load? Can I wire the pump straight to the an aftermarket relay and switched B+?
02-16-2006, 12:10 PM
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What is the current draw on the Walbro pump? Most of the aftermarket LP's need an interposing relay because the factory LP circuit is very close to the fuse rating. You may have cleared that fuse. I use the factory wires from the LP to trigger my relay and pull the pump in from the relay.
02-16-2006, 12:15 PM
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What is the current fuel pressure at the CP3 ?
What is the voltage at the terminals of the Wablro with the engine idling ?
"It also smoked and had low power. "
Put the scanner on it and watch the rail pressure. My guess is that the CP3 is fried due to low flow from the lack of flow from the previous lift pump.
Dealers have real problems troubleshooting power and fuel system problems on these trucks. I suspect they are using the Walbro as an excuse. PM me if you need further help.
What is the voltage at the terminals of the Wablro with the engine idling ?
"It also smoked and had low power. "
Put the scanner on it and watch the rail pressure. My guess is that the CP3 is fried due to low flow from the lack of flow from the previous lift pump.
Dealers have real problems troubleshooting power and fuel system problems on these trucks. I suspect they are using the Walbro as an excuse. PM me if you need further help.
02-16-2006, 12:21 PM
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"What is the current draw on the Walbro pump?"
Typically between 4 and 6 amps at the pressures on a Dodge truck. But a blocked fuel filter can take the current higher. According to the shop manual, the 05s are relay driven, not directly ECM driven. I am not sure about other engines that had the lift pump mounted on the engine.
"Most of the aftermarket LP's need an interposing relay because the factory LP circuit is very close to the fuse rating. You may have cleared that fuse."
The 05 fuse rating on the lift pump circuit is 20A and there is little other equipment on that circuit. I'm pretty sure the lift pump relay would handle 10A without too much trouble.
Typically between 4 and 6 amps at the pressures on a Dodge truck. But a blocked fuel filter can take the current higher. According to the shop manual, the 05s are relay driven, not directly ECM driven. I am not sure about other engines that had the lift pump mounted on the engine.
"Most of the aftermarket LP's need an interposing relay because the factory LP circuit is very close to the fuse rating. You may have cleared that fuse."
The 05 fuse rating on the lift pump circuit is 20A and there is little other equipment on that circuit. I'm pretty sure the lift pump relay would handle 10A without too much trouble.
02-16-2006, 01:43 PM
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Walbro . . . con't
Just got back from picking it up at DC . . . the tech thinks it's a ECM interface problem with the Walbro. It smoked and had little power for the 30 miles home, although at first, when cold, it seemed to run much better. It had 18-20 psi FP at idle. I'll go measure voltage at idle on the Walbro. I hope the CP3 isn't fried . . . tech said only codes thrown were low FP. I don't think it's running at all. Can indicated FP be from the CP3 pulling fuel?
02-16-2006, 01:54 PM
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If you have 18-20 PSI at the CP3, then the Walbro is running exactly as it should. (We've found the pressure at the injection pump to be higher on Dodge trucks than my Ford because the RETURN line is a bit restrictive.)
The only thing the CP3 feedpump can do is make a vacuum. It is not capable of making pressure at the inlet of the CP3.
Check the Walbro voltage (and polarity) and if it is good, there is nothing wrong with how it is being powered.
Check your owners manual to see if there is a fuel pump relay as well.
It sounds to me like the Walbro is running fine.
I think your low power and smoke issue are coming from someplace else. Monitoring rail pressure is the first step in isolating that problem. Your dealer should have understood that.
The only thing the CP3 feedpump can do is make a vacuum. It is not capable of making pressure at the inlet of the CP3.
Check the Walbro voltage (and polarity) and if it is good, there is nothing wrong with how it is being powered.
Check your owners manual to see if there is a fuel pump relay as well.
It sounds to me like the Walbro is running fine.
I think your low power and smoke issue are coming from someplace else. Monitoring rail pressure is the first step in isolating that problem. Your dealer should have understood that.
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02-16-2006, 02:27 PM
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"I got 12v to 14v on a reading across the Walbro with 18-20 psi on the FP gauge at top of the FF."
That is reading PRE filter pressure, just so you know.
It sounds like the Walbro is running just fine. Your problem lies elsewhere. Any idea on why the voltage is varying ?
BTW: Do you have a part number for the OEM wiring harness that you could share with us ?
That is reading PRE filter pressure, just so you know.
It sounds like the Walbro is running just fine. Your problem lies elsewhere. Any idea on why the voltage is varying ?
BTW: Do you have a part number for the OEM wiring harness that you could share with us ?
02-16-2006, 02:50 PM
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Walbro . . . con't
Don't know about the varying voltage except it always fluctuates when I first start these CTD's. Superduty, you didn't comment on the 1/4" fuel tube I used as a by-pass - Is that a minor thing?
02-16-2006, 02:54 PM
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The 1/4" bypass is fine.
If you have 18 PSI at the FF, you probably have 13-15 PSI at the CP3, with about 75 GPH going by the inlet. Your CP3 has tons of fuel going to it. The return line provides most of the restriction.
Pressure wise, CP3s only need a few PSI. What they need most is good flow and yours will have lots. (Your engine probably needs 25 GPH and you've got 70+).
The only way that you could be starving your CP3 is if the readings you are giving are false by the combination of:
- the fuel filter being plugged
- the Walbro being defective or starved for power such that it only makes 20 PSI.
Highly doubtful.
Otherwise, what I think you have is 75 GPH going by the CP3 inlet through the return line. The restriction of the filter, supply and return lines creates the restriction to build the 20 PSI at the FF.
It sounds like it is running just like mine. I have 30ish PSI on my FF, but I run a second 2 micron filter and my bypass is 3/16", not 1/4". But there is nothing wrong with your 1/4" bypass either.
If you have 18 PSI at the FF, you probably have 13-15 PSI at the CP3, with about 75 GPH going by the inlet. Your CP3 has tons of fuel going to it. The return line provides most of the restriction.
Pressure wise, CP3s only need a few PSI. What they need most is good flow and yours will have lots. (Your engine probably needs 25 GPH and you've got 70+).
The only way that you could be starving your CP3 is if the readings you are giving are false by the combination of:
- the fuel filter being plugged
- the Walbro being defective or starved for power such that it only makes 20 PSI.
Highly doubtful.
Otherwise, what I think you have is 75 GPH going by the CP3 inlet through the return line. The restriction of the filter, supply and return lines creates the restriction to build the 20 PSI at the FF.
It sounds like it is running just like mine. I have 30ish PSI on my FF, but I run a second 2 micron filter and my bypass is 3/16", not 1/4". But there is nothing wrong with your 1/4" bypass either.
02-16-2006, 03:00 PM
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Originally Posted by MaroonCumminsInOre
Don't know about the varying voltage except it always fluctuates when I first start these CTD's. Superduty, you didn't comment on the 1/4" fuel tube I used as a by-pass - Is that a minor thing?
02-16-2006, 03:01 PM
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I'm not sure. Electrical wise any VPW J1850 scanner will work. Software wise I am unsure if the rail pressure command is generic or unique to the Cummins. I suspect it is part of the generic J1850 command set.
02-16-2006, 03:06 PM
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How does it start ? Long crank ? Short crank ?
The things to check are:
a) does the rail pressure build properly ? You should see 20,000+ PSI at WOT. I think the spec is 1600 bar, which is 23,500 PSI.
b) check the boost level. I'm not sure what the spec is on this.
c) Check the engine load factor and make sure it is going to 100%.
If rail pressure is lacking, check the return flow on the injector leakage line and the rail pressure relief valve.
If all of that is good, you are down the CP3 being the problem.
The things to check are:
a) does the rail pressure build properly ? You should see 20,000+ PSI at WOT. I think the spec is 1600 bar, which is 23,500 PSI.
b) check the boost level. I'm not sure what the spec is on this.
c) Check the engine load factor and make sure it is going to 100%.
If rail pressure is lacking, check the return flow on the injector leakage line and the rail pressure relief valve.
If all of that is good, you are down the CP3 being the problem.