Alright you gurus... 1979 116 300SD, have to really pump accel. to start on occasion, not all the time. Glo plugs are new. It seems fuel system bleeds down though all connections are tight.

It's in shop now and Indie has checked all connections. If you pump primer pump, fires right now, no problem.

Could injectors bleed down or the pump be doing something wierd?

Love the car, hate the issue.

Thanks

Do you see diesel leaks anywhere? Try changing the primer pump.. they aren't that expesnive and they do go bad.

I don't think pumping the accelerator is going to do anything to help you start your car except maybe make you think you are doing something useful. Unlike gasoline cars there is no accelerator pump in a Diesel system, so you are not adding any extra fuel by pumping the acclerator. Still it does no harm and probably makes you feel better.

I had the same problem with my Chevy 6.2 Diesel. I found a small leak in the line from the tank to the pirmary filter. The filter was above the level of the tank so when the truck stopped the fuel would slowly syphon back to the tank. A tighting of all hole clamps and fittings solved the problem.

No leaks, all connections seem tight, no puddles. New fuel filters, etc.

Could the IP or injectors be leaking down somehow?

Any direction would be appreciated, I'll replace anything that might work, trunk seal, muffler, injectors, wheels, etc.

Thanks

Did you recently change the secondary (big) fuel filter? I had the same problem a few weeks ago. There's a little o-ring on the big bolt that holds the fuel filter in place. Remove the secondary fuel filter, pull that fixing bolt out of the filter bracket, and replace that o-ring. May not be the culprit, but doesn't cost much to eliminate this possibility.

Shark,
For air to be in the system, the fuel must be leaking out, or back to the tank.
If there is no fuel leakage from the engine, then the fuel must be going back to the tank.
The lift pump (including primer pump) has non-return valves as part of it. If these are working correctly, no fuel should leak back to the tank from upstream of the lift pump. So, if there were a leak on the tank side of the lift pump, your engine should start and run for a short time then stop when the air hits the IP.
As this is not your symptom, then the non-return valves in the lift pump must be allowing the fuel to return to the tank. This may be because of O-ring issues, which cause leaks from the Primer Pump (replace with the new style) or because the lift pump itself needs an overhaul.

Even if the non-return valves are faulty, there should be no problem IF there is no way air can get into your fuel system upstream of the lift pump. You must have an air leak into the fuel system.
If you repair the lift pump, you may soon find the leak, as lift pump efficiency will improve markedly.

__________________
Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.

Tony:

Thanks, that makes some sense, I'll see what I can do and I think I'll have the injectors pop tested for the hell of it while I'm at it. Other than the bleed down occasionally, it's perfect.

Read about nozzles before you let them sell you on a new set. They always want to sell you a new set of nozzles and you may end up poorer and with worse injectors for it.

Good point, I've got a friend with a shop that trusts his injector shop, the guy gave me a price to bring them in and have him test them or a price for him to do the work, not too much of a hustler, I think.

I should add that on my original problem, if I pump the primer before hand, she fires quickly.

in a time long ago, when i was a materials relocation engineer, we had some air leaks without fuel leakage. air was getting in without fuel leaking out. they drive you crazy till you find them. but they were in truck engines that are easier to work on. so, even though all connections are tight, they can still leak.
that said, still check your primer pump first. cheapest and easiest.
roberto

__________________
Current money-pits:
96 Passat TDI
78 300D 100k miles(60miles/day)FOR SALE
91 Jetta Diesel 250k miles (80miles/day)
82 Toyota Diesel pickup 150k miles; out of service for a little while with a valve problem.
All on BelenBioDiesel
Past diesels:
01 Golf TDI
81 Isuzu P/U
85 Jetta
89 KW 425 cat
85 Pete 400 cat (currently still running the west coast with over 1.5 million miles)
81 KW 400 Cummins
77 Freightliner CO ???? Cummins (Buttercup)
57 180D lots of miles(gone but not forgotten)

Replace the suction line between the lift pump and the metal line from the tank, it's leaking air from cracks. This will eventually make it almost impossible to start the car.

If you still have the red topped "unscrew and pump" style hand pump, it's leaking, replace it with the new "thumb" pump that's completely sealed, all you have to do is push it down. Much nicer, won't dump fuel all over you when it's leaky.

Also, check the crankcase oil for fuel dilution. It's possible the IP is worn and is leaking the fuel out into the crankcase oil. This will cause hard starts when there is air in the IP, but will also rapidly destroy the engine.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Have you tried that o-ring? I was sceptical, as well, but I had the identical problem and that little piece of rubber solved it.

I bought an '85 300SD a week ago, very pleased so far. The pre-filter plastic was clouded but I could tell there was muck in it, so just changed both fuel filters.

First, a person with experience told me what to do: clamp off fuel line from tank; replace pre-filter; loosen big bolt holding primary filter; spin off primary filter and replace; tighten big bolt; loosen small bolt securing fuel lines; unclamp fuel line from tank; use primer pump to fill big filter, 'til bubbles don't come out loosened fitting; tighten fitting; start car, and be prepared for rough spots 'til air is worked out of system.

I did all this, and car started right away, got rough, then stopped. Since then, it won't start. I feel reasonably confident that it's an air in fuel system problem, but I hate to just sit there and crank away, draining the battery, if there's anything else I can do or check. I've already been at it for a while.

Primer pump is leaky, that's for sure, but it was leaky before this started and I've got it well screwed-down and it seems tight.

Does anyone have a suggestion? Many, many thanks!

Cam:

Replace the primer pump, if it leaks fuel out while pumping, it leaks air in while running, and you now have an IP full of air.

Get the thumb type, not the screw-down type.

When the new one is installed, pump until you hear fuel hissing out the pressure relief on the main filter. This will take quite a while, believe me!

Then attempt to start. If it won't fire right away, loosen the injector lines at the injectors about half a turn, and crank until no more air comes out, then tighten, run the glow plugs, and it should at least hit some.

Takes a while to get it going again when you get air into the IP and injector lines.

You will probably need to charge the battery several times.

In the future, just fill the new filter with clean diesel fuel, and only change filters with a hot engine. It will crank faster, start instantly, and if the new filter is full (I'd prime it with the hand pump, too), it should run long enough to bleed everything.

The OM603 doesn't have a hand pump, so all you can do is fill the filter. Never had a problem on mine, starts right up, runs rough a couple seconds sometimes, then troublefree.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I too had some rough idle and troulble starting... I replaced the primer pump... a little better, then I replaced the fuel filters... even better... then I noticed severe deterioration of the rubber fuel lines... the one between the primary fuel filter and the pick-up pump was actually split , so I replaced those rubber hoses and she runs well now .

__________________
Sincerely,
Tommy Darcy
----------------
'82 300D (Turbo) c300k miles, "Mary."
:wtf: