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Air in fuel system?

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fuel
2K views 11 replies 4 participants last post by  Red90 
#1 ·
So I replaced the fuel filter on my 1991 200Tdi (original, not transplant). I was rushing and forgot to fill the new filter prior to installing it. Turned the key and as expected the engine fires off fine, then dies when it gets starved of fuel. I realize my mistake, open the bleed screw on the filter housing and begin pumping the manual lever on the lift pump with no result. I do a search here and find that if the lift pump is resting on the high point of the cam, the manual lever will not work. I try turning the engine over a few times, but can not find a spot that will get the lift pump working, but the engine lights off on one of the tries and runs fine at all rpm and load ranges. So i'm guessing the lift pump is good, I just wasn't getting it low enough on the cam to work.

I've tried using the lift pump to prime the system 20 different times, but can not get it to move fuel. I've filled the filter through the banjo bolt opening, and ensured fuel is returning to the pump by opening the pump-to-tank return line and turning over the motor.

So the engine is completely fine once started, but now takes 3-5 cranks to start (previously fired off on first crank every time). When I turn it over it sounds like the starter is engaging normally, but then changes tone to a whizzing noise. Do this a couple times and it fires off and runs fine, but obviously now I'm wondering why the trouble starting.

Am I chasing an air in the fuel system problem, or did a starter problem crop up at coincidental time, or is there something else I'm missing?

Thanks for the help.
 
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#2 ·
The lift pump is probably dead. The system is self purging and will work without the lift pump as long as there are no air leaks. The injection pump can suck from the tank on its own. I ran with a dead lift pump for a solid year or two.

To check the lift pump:

1) Remove the wire from the injection pump solenoid.

2) Disconnect the tube between the lift pump and the filter at the filter.

3) Stick the tube in a bucket.

4) Crank the engine. If the pump is working, you will get a good flow of fuel.

If it is dead and you do not have a sedimenter, add one. Any tiny bit of dirt will jamb the non return valve on the pump open.
 
#3 ·
The whizzing noise on the starter means the bendix is not engaging properly. They get dirty and do that. Get a Robert Davis 3.1 kW starter and you will never hear an engine spin so fast.
 
#4 ·
Thanks for the response. I'll check the lift pump in the morning (my wife doesn't think spending the day in the garage is appropriate for Thanksgiving...). For the starter, is the best way to reach him through PM on here in the forum?

Thanks again.
 
#6 ·
Thread revival

Thread revival:

So I'm still waiting to receive my 3.1 starter. Someone please take a listen to this video and make sure I'm correct in that the starter is the issue. I'm asking for help because while I consider myself fairly mechanically inclined, diagnostics come with experience. This morning I decided to try firing up the Defender and it did the same thing its been doing, then about five attempts in it started right up. Over the course of the day I started it 15 times with no issues after the first time.

Prior to changing the fuel filter it had never once had an issue starting. I cant help but think it is a fuel issue.

Thanks for the help.
 
#10 ·
I've also had a recent failure on my 300tdi that was similar. Turns out that the spill rail hoses were starting to leak diesel (and therefore air into the rail). After it sat overnight it wouldn't turn over unless I manually primed the lift pump.

So I'll be replacing the whole rail. It's cheap, and on an engine that's 25 years old, I figure that it owes me nothing.
 
#11 · (Edited)
Red, thanks. I ordered a starter you recommend, it just has been delayed several times getting from rdavisinva to me. Hopefully mid month I’ll have it. It was just strange that after the first time firing it up yesterday, it worked like a charm the rest of the day. The lift pump is dead & will be replaced shortly.

Sonoronos, I haven’t pulled the starter because I don’t have the new one on hand. And while it wasn’t working ever turn, I can get it started if I’m patient. Plus it looks like a complete pain in the a$$ to get it out. I didn’t wsnt to start that process until I knew I could get the new one in.
 
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