Pump shut down after battery short

nedbread

Member
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Location
austin, texas
Hi all,

I was driving on the highway and the truck stalled. I coasted to a stop and checked under the hood. It seems I did not tighten down the battery while working on it recently and the 24V battery post touched the frame. Tightened that back up but the truck would not start. (Turns over fine) Fuel is coming into the IP from the fuel pump but nothing comes out at cracked injectors (no matter how many times I crank it). Maybe something with a relay to the IP? The pump makes a click when it gets power but I haven't tested any voltages. Most likely I can read voltages at various points and determine what is going on-- anyone familiar with where that electrical diagnosis procedure can be found?

best wishes,
Ned
 

Skinny

Well-known member
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Portsmouth, NH
That is strange because in theory if the IP clicks with power applied then fuel should come out of the injection lines if its going into the IP. Sure you coule have a 1 in a million chance the solenoid is clicking but not actually working.

The other issue is that the IP is 12v. In theory if the second battery terminal was odd, it would only affect the glow plugs and starter.



Sent from my SM-T380 using Tapatalk
 

nedbread

Member
32
11
8
Location
austin, texas
That is strange because in theory if the IP clicks with power applied then fuel should come out of the injection lines if its going into the IP. Sure you coule have a 1 in a million chance the solenoid is clicking but not actually working.

The other issue is that the IP is 12v. In theory if the second battery terminal was odd, it would only affect the glow plugs and starter.



Sent from my SM-T380 using Tapatalk

Thanks Skinny and @eric67camino
Yes I agree. Fuel comes out of the rubber fuel supply line on the right hand side of the fuel filter that goes under the air intake to the IP. The pink wire that connects to the shutoff solenoid has 12.6V.
 

chevymike

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Location
San Diego, CA
That is strange because in theory if the IP clicks with power applied then fuel should come out of the injection lines if its going into the IP. Sure you coule have a 1 in a million chance the solenoid is clicking but not actually working.

The other issue is that the IP is 12v. In theory if the second battery terminal was odd, it would only affect the glow plugs and starter.



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Having just gone through this issue myself, my solenoid would "click" but I wasn't getting any fuel through. After testing/trying a bunch of things, I decided to replace the solenoid anyways, with a good German made unit. When I compared the two, when installed, my old one "clicked", the new one "CLICKED".

Basically determined that though you would hear a click, it wasn't enough to pull the fuel cutoff valve open to get fuel into the pump. To me, the click test is more a confirmation that you are getting power to the solenoid but not that it is actually opening the valve. After replacing, no issues starting/running.

This is the one I bought, https://www.amazon.com/gp/product/B07KQQ3BTG
 

nedbread

Member
32
11
8
Location
austin, texas
Having just gone through this issue myself, my solenoid would "click" but I wasn't getting any fuel through. After testing/trying a bunch of things, I decided to replace the solenoid anyways, with a good German made unit. When I compared the two, when installed, my old one "clicked", the new one "CLICKED".

Basically determined that though you would hear a click, it wasn't enough to pull the fuel cutoff valve open to get fuel into the pump. To me, the click test is more a confirmation that you are getting power to the solenoid but not that it is actually opening the valve. After replacing, no issues starting/running.

This is the one I bought, https://www.amazon.com/gp/product/B07KQQ3BTG
Thanks!

Did yours fail in a similar way where you had a short or what caused it?

Ned
 

cucvrus

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Probably 35 years of use. These aren't late models vehicles anymore. They are antiques. When I started buying them they were 9 years old. That is comparable to a 2012 Chevrolet truck today. Good Luck.
 

chevymike

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Thanks!

Did yours fail in a similar way where you had a short or what caused it?

Ned
Nope, just driving along and it acted like it was running out of fuel and finally died. Luckily I was able to get off the road. Would not restart. Had it towed home and started troubleshooting. Did new filter and was able to blead it without problems, cleaned the return check ball and made sure the return line was able to get air into the fuel tank. Bowl area of the IP had clean fuel. Put a clear return line off the IP housing and no air bubbles. Cracked all 8 injectors and even pulled the glow plugs out to allow it to spin a little faster. I was not getting any fuel out of the injector lines, which left either a bad solenoid or bad IP. Solenoid was a cheap method to try. It seems to fixed the problem.

My guess is, when yours shorted out, it somehow allowed 24v to reach the solenoid which is only rated for 12v. Likely damaged it. I could also just be coincidental, which does happen. Like cucvus said, they are 35 years old.
 

Skinny

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Do yourself a favor, replace the check valve while taking the cover off. Probably wouldnt hurt to turn the fuel screw an 1/8. 1/4 if you are feeling frisky. Both of my CUCV engines went a 1/4 with practically no smoke. Way too low on fueling.

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Keith_J

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Schertz TX
Turning up the maximum fuel is something that should only be done if you have an exhaust gas temperature gauge. The plungers rarely get stuck to where it limits fuel.
Smoke is not a good indication of maximum fuel, by the time you get smoke, you could be well over 1200 °F.
 

nedbread

Member
32
11
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Location
austin, texas
Thanks all,

As of right now I am still just trying to get fuel out of the injectors. The consensus seemed to be replace the fuel shutoff solenoid, so I did that. Still no fuel out of the injectors, killed the batteries after 5 or 6 cranks. (Oddly after they still both showed 12+V but the starter wasn't doing much). Charging the batteries and will try again. I remember it taking a good few cranks to prime...

Best,
Ned
 

cucvrus

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You can have 12 volts in a battery and it is scrap. Most importantly is CCA. You must check the Cold Cranking Amps. Check this out and get the batteries load tested. Weak battery's are the root of all evil that happens to the CUCV starting and glow plug system. No need for modifications to the electrical system. Just maintain and keep the stock system maintained and good strong batteries. Replace batteries in pairs. Not 1 at a time. Load test and then resume your efforts. Good Luck.
 

Keith_J

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Schertz TX
Starting the engine will bring voltage down to 10.5 volts each..more voltage loss at the terminals.
I have not measured the required voltage for the fuel shutoff solenoid but it is possible. Solenoid coils have a knack of pulling a good in rush current, causing significant voltage drop. Check all connections and measure voltage at the pink terminal during cranking. Or you can avoid the Soldier B issue by connecting the pink wire terminal to front battery positive terminal.
 

nedbread

Member
32
11
8
Location
austin, texas
Fuel supply line to IP has pressure
No fuel in injector lines (verified by disconnecting one of the injector lines from the IP under the air intake manifold)

Shutoff solenoid
  • 11.3V
  • 8.5V during cranking

Battery 1
  • 12.35V
  • 12.35 during cranking (I had a little Lithium jump starter on it that might be why it didnt go down)

Battery 2
  • 13.25V
  • 10.5 during cranking
According to TM9-2320-289-34 (page 2-16) shutoff solenoid should be 9V during cranking... this could be the issue

@Keith_J I guess I can try this... connect the pink wire to the first battery... would verify the pump works...

Thinking of what to try next.
 
Last edited:

cucvrus

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At this point I would tap out and get the injection pump rebuilt. I know it is like $450. for everything but it is the next move. the avoiding the injection pump rebuild dance is over. Time to get real and get it done. Make sure you get a dated pump old out dated injection pump. I learned that a time or 2.
1986 CUCV M1009 Decade after being wrecked. | Page 35 | SteelSoldiers

Good Luck. It is a fairly easy replacement item.
 

nedbread

Member
32
11
8
Location
austin, texas
Thanks, the IP was replaced in February. This is a problem that arose because of a short of the 24V terminal to ground while driving. Other than a sort of "top gear" stall nothing funny happened except the vehicle cranked without starting. If there is some reason to think the pump might have broken I can replace it again. I called the company that sold me the pump and they suggested replacing the shutoff solenoid which I did.

edit: wired the 12V terminal directly to the shutoff solenoid as per @Keith_J 's suggestion. This gave a much louder CLACK than I was used to and the dash lights didnt do anything when I put the key in, but it cranked with the solenoid voltage showing 9V+ and no fuel comes out of the IP right at the lines as before.

As @cucvrus says maybe the pump but it is "new" from pensacoladiesel.
 
Last edited:

Keith_J

Well-known member
3,105
181
63
Location
Schertz TX
Fuel supply line to IP has pressure
No fuel in injector lines (verified by disconnecting one of the injector lines from the IP under the air intake manifold)

Shutoff solenoid
  • 11.3V
  • 8.5V during cranking

Battery 1
  • 12.35V
  • 12.35 during cranking (I had a little Lithium jump starter on it that might be why it didnt go down)

Battery 2
  • 13.25V
  • 10.5 during cranking
According to TM9-2320-289-34 (page 2-16) shutoff solenoid should be 9V during cranking... this could be the issue

@Keith_J I guess I can try this... connect the pink wire to the first battery... would verify the pump works...

Thinking of what to try next.
Try that lithium ion booster on the front battery to assure voltage during cranking.
 

Keith_J

Well-known member
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181
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Location
Schertz TX
Since you have had the IP off, double check the function of the pump internals and correct assembly of the cover to pump. The governor pushes the linkage back, turning the metering valve closed. This is also how the shutoff cuts fuel flow. If the linkage does not move forward under spring force and rotate the metering valve open, there will be no fuel flow.

This linkage must operate freely without any binding, idle governing relies on tiny forces.
 
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