Problem with Bosch VE pump on 4BT....

[JimmieD]

Thanks, Norm!

Yes, just as you describe. Interesting that Cabell Garbee just contacted me because his 4BT is doing exactly the same thing! As Norm said we figure it's the ignition switch [el cheapo aftermarket on mine] that simply can't carry enough current to keep fuel solly open while cranking that fat Cummins starter.

Took solenoid out of VE pump, a very large pain, and fixed an o-ring that was jammed on fuel shutoff plunger shaft. Reassembled and no change at all.

My cure was the typical JimmieD type fix. I fabbed up a dandy new aluminum toggle switch panel as a place to also mount the new pushbutton starter switch! :~ )

Best thing that could ever happen in the long run. I now know FAR more about these little 4BT's and their injection system for future troubleshooting, maintenance and repair. No longer a complete diesel dummy.

Thanks!

JimmieD

[Charles Talbert]

What you need

It should be set up as follows: A separate solenoid should be mounted on the fire wall near the starter. This solenoid is activated by the switch in the cab, the fire wall mounted unit activates the starter solenoid & the fuel shut down solenoid. The newer engines have wire gauge limitations as far as shut down activation. There is a pull off lead that is activated at the same time the starter engages & a hold off lead that is activated by the ignition switch being turned on. Uses 14 gauge wire if under 4 feet in length, 12 gauge if over 4 feet. The fire wall unit needs 8 gauge main leads, feed from the battery cable terminal on the starter, delivery is back to the starter solenoid activation terminal.

[JimmieD]

Thanks for adding that Charles, as that jumper from firewall [actually fender] mounted solenoid is part of what I did. I'll have to e-mail Cabell and remind him. However with that setup, but without separate pushbutton, the truck still wouldn't start! Junk switch can't carry any real amps. Geeee, I wonder where it's made?

[Charles Talbert]

Thanks for adding that Charles, as that jumper from firewall [actually fender] mounted solenoid is part of what I did. I'll have to e-mail Cabell and remind him. However with that setup, but without separate pushbutton, the truck still wouldn't start! Junk switch can't carry any real amps. Geeee, I wonder where it's made?

If amperage capacity is your problem, the fender mounted switch may not be good, it takes very little capacity to activate the solenoid. It's what is going across the actual solenoid contacts that counts. A solenoid with silver contacts is a BIG plus also, these are much better.

[JimmieD]

I'm forgetting what I even did to get it running, Charles! Okay, went and checked it again. I now have a lead running direct from ignition switch 'Run' position to the fuel solenoid & KSB connection. I have 2 starter pushbuttons, one under hood, one in dash panel. Both of these are wired direct to full battery voltage. Underhood switch is covered so I don't hit it by accident!

The ignition switch is able to carry starter current to crank engine, and is able to open fuel solenoid for fuel flow. Problem is it apparently can't walk and chew gum at the same time, so push button is needed under all cuircumstances. Cabell just came up with the same problem! Very strange and can't say I fully determined the exact problem.

Oh, and thanks again for the assistance with bypass filtration system!

[CGarbee]

Hmm, mine was just a bad solenoid... Was working fine, then was a bit rough starting one week (and had lost a little off the top end and was a bit sluggish), than refused to start one morning.
After doing a bit of diagnostics (ensured that I was getting good, clean fuel to the injector pump and that the power feed to the solenoid was providing power as it should), I swapped out the solenoid using the on-line source that JimmieD located since it was a lot less then an over the counter part locally (funny thing, it ended up getting shipped out of my local CarQuest warehouse...).
Truck starts and runs like normal. Old solenoid had died (was in a 1990 engine that I have had for ten years, so I know it was at least ten years old, if not seventeen...).

Thanks for thinking of me :) (and for the help, Jim)

[JimmieD]

I removed and disassembled my solenoid, finding the solenoid plunger to be jammed up by the o-ring. Straightened things out and put the o-ring back on the bottom of solenoid where it belongs. Reassembled and tested and same story. Will only work with an ignition switch fired lead to solenoid and separate starter pushbutton.

I may eventually replace the solenoid although it seems to function perfectly once the wiring is changed as per above. New ignition switch didn't help either. Removal of VE injection pump support plate makes it easier to access the solenoid, but this requires removal of one 10mm, 2 #25 Torx, 2 @ 5mm allen and you have to be triple jointed to access them all. Next time I feel like punishing myself I'll do the R & R.

The starter solenoid on fender easily carries the current to crank the starter but it could be weak enough that it can't also pull solenoid plunger though I doubt it. What is strange is that even if the fuel solenoid is fired by the control circuit wire from ignition switch to solenoid, not the heavier wire to starter, it still won't open fuel valve and crank starter simultaneously. A second wire from pushbutton to starter solenoid is needed. More investigation is needed also.

Here's the link for anyone needing a Bosch VE pump fuel shutoff solenoid for a Cummins. It uses the same solenoid as 74-81 VW Dasher, 85-89 VW Golf, etc. and link has them at 1/3 Cummins price!

http://www.autopartsauthority.com/oe...~oemparts.html

Glad it worked out for ya Cabell! :~ )