Question about inj pump

lyeinyoureye · Post by **lyeinyoureye** » Wed Jul 18, 2007 4:03 pm

If I put in a kill switch for the pump solenoid, could I coast downhill with the engine in gear safely and no fuel being injected, or would I risk screwing up the inj pump since the engine's spinning but it's not operating?

VWCaddy · Post by **VWCaddy** » Wed Jul 18, 2007 4:41 pm

The cut off solenoid just lets fuel bypass the pump with none being injected. It basically does not let the pressure rise enough to get through the injectors so all flows back to the tank via the return line.

hagar · Post by **hagar** » Wed Jul 18, 2007 5:01 pm

hagar can see NO problem ---- I do that lot's of times ---remember the Vane pump is still running ----BUT read ALL by Andrew in Flagstaff AZ

hagar.

82vdub · Post by **82vdub** » Wed Jul 18, 2007 5:45 pm

lyeinyoureye - why would you want to cut the fuel off to the engine, keep the engine turning going downhill? Are you trying to get some sort of engine braking?

lyeinyoureye · Post by **lyeinyoureye** » Wed Jul 18, 2007 5:46 pm

Awesome, thanks for the info! The more I look at it, the more robust VW's diesel setup seems.

82vdub wrote:lyeinyoureye - why would you want to cut the fuel off to the engine, keep the engine turning going downhill? Are you trying to get some sort of engine braking?

Yup, engine braking w/o fuel use.

82vdub · Post by **82vdub** » Wed Jul 18, 2007 5:51 pm

IMHO, I think that fuel consumption is so small with these cars that shutting if off or things like that probably don't matter much in the overall scheme of things. If you're not careful, you may overheat the engine and melt a piston. I know that the fuel actually cools the piston in a gas engine, and I can only suspect the same thing with a diesel engine.

lyeinyoureye · Post by **lyeinyoureye** » Wed Jul 18, 2007 5:57 pm

Iirc, a richer charge will help cool the intake charge at WOT for gassers to help avoid detonation, but for any load lesss than that it wouldn't do much. I don't see how I could melt anything in a diesel if there's no fuel in there. If anything it'd cool down the engine, which is what happens on my FI gasser, and from what I've heard, happens on TDIs once they get to their idle fuel cut for a significant amount of time.

hagar · Post by **hagar** » Wed Jul 18, 2007 7:04 pm

a WARNING : the wire to valve may NOT be fused ----so insulate wires to switch--REAL GOOD.

hagar.

lyeinyoureye · Post by **lyeinyoureye** » Wed Jul 18, 2007 9:34 pm

It's a diesel in what used to be a gasser, so iirc it should be fused (fusible link?) in some way, since I'm using the black wire to what used to be the ignition coil for it, but I should take a real look just to make sure.

Vincent Waldon · Post by **Vincent Waldon** » Wed Jul 18, 2007 9:44 pm

I've always wanted to do this.... used to shut off the idle solenoid on my old VW van for the same reason.... mounted the pushbutton switch into a T handle shift knob.

Please let us know if you get any appreciable braking from it ??

thanks,

Vince

lyeinyoureye · Post by **lyeinyoureye** » Wed Jul 18, 2007 10:05 pm

Sure thing.

Post by **Fatmobile** » Thu Jul 19, 2007 3:24 am

The wire going to the pump is much smaller than the fuseable link so don't expect the fuseable link to save you.
I think hagar is right, for sure the Rabbits aren't fused going to the stop solenoid,... it's the same wiring for the gasser to the coil. I've swapped the engine bay wires, gasser to diesel conversion, a couple times.

82vdub · Post by **82vdub** » Thu Jul 19, 2007 9:39 am

Just curious as to the reason why VW wouldn't have fused the stop solenoid? I'm pretty sure it't not fused, I've put a wrench on the wire connection with the key on by mistake and didn't toast any fuses.

Former VWDieselParts.com Forum

Question about inj pump

Question about inj pump

BOSCH I P 107 A types.

Fues shut off.