Priming the Fuel System

[mac.man25]

So I need to get my fuel system all primed and stuff, but my service manual (Hayns) says not where to look for the priming pump/how to do it.

So where is this elusive pump?  And if it doesn't exist, then how do I remove the air from the fuel lines?

Cullen

[mac.man25]

Oh, sorry, the car is an '86 Golf NA 1.6L

[jtanguay]

get a vacuum pump and hook it up to the return line on the injection pump.  create a vacuum there and it should suck the fuel right from the tank keep sucking until fuel comes out and that should be fine.

these cars never came with a priming bulb have they??? stupid haynes... forgot to tell you to buy it! hehe

[hipifreq]

The fuel priming pump used to be located on the fuel filter assembly, but VW got rid of it just after introducing the 1.5L diesel.

My Bentley (for the 1.5/1.6L diesel Dasher from 80-81) says that the best way to prime the pump is to remove the wire from the fuel shutoff selenoid, then loosen all the fuel lines at the injectors. Crank the engine until fuel flows through the fuel supply lines. Tighten the lines and replace the wire at the selenoid.

[jtanguay]

The fuel priming pump used to be located on the fuel filter assembly, but VW got rid of it just after introducing the 1.5L diesel.

My Bentley (for the 1.5/1.6L diesel Dasher from 80-81) says that the best way to prime the pump is to remove the wire from the fuel shutoff selenoid, then loosen all the fuel lines at the injectors. Crank the engine until fuel flows through the fuel supply lines. Tighten the lines and replace the wire at the selenoid.

good for bleeding small bubbles/air pockets, but for a completely dry pump, you will need to either prime it with a priming pump, or a vacuum pump.

[mac.man25]

The fuel priming pump used to be located on the fuel filter assembly, but VW got rid of it just after introducing the 1.5L diesel.

That's dumb, they should have kept it easy.

My Bentley (for the 1.5/1.6L diesel Dasher from 80-81) says that the best way to prime the pump is to remove the wire from the fuel shutoff selenoid, then loosen all the fuel lines at the injectors. Crank the engine until fuel flows through the fuel supply lines. Tighten the lines and replace the wire at the selenoid.

Hummmmm, that would be a crapload of cranking.  I think even my dual battery setup would die before that was finished.  Or the starter.  No matter, tomorrow my friend is coming over with a hand vacuum pump, we're going to see if the lines from the tank are in any shape at all.

It was suggested that I spray out my engine compartment with soap from a carwash to get all the sprayed Diesel off all the engine stuff.  Is that safe?  I've never really done that with a car and I'm not sure how well all the electirical connections in there would do.  Any suggestions?

[jtanguay]

The fuel priming pump used to be located on the fuel filter assembly, but VW got rid of it just after introducing the 1.5L diesel.

That's dumb, they should have kept it easy.

My Bentley (for the 1.5/1.6L diesel Dasher from 80-81) says that the best way to prime the pump is to remove the wire from the fuel shutoff selenoid, then loosen all the fuel lines at the injectors. Crank the engine until fuel flows through the fuel supply lines. Tighten the lines and replace the wire at the selenoid.

Hummmmm, that would be a crapload of cranking.  I think even my dual battery setup would die before that was finished.  Or the starter.  No matter, tomorrow my friend is coming over with a hand vacuum pump, we're going to see if the lines from the tank are in any shape at all.

It was suggested that I spray out my engine compartment with soap from a carwash to get all the sprayed Diesel off all the engine stuff.  Is that safe?  I've never really done that with a car and I'm not sure how well all the electirical connections in there would do.  Any suggestions?

Electrical connection's on a diesel??? maybe just dry off the solenoid... thats pretty much all you need to worry about.  I remember washing gasser's and them running like complete crap afterwards.  Not with a diesel (unless you have a cone filter and manage to get it really good and wet!!! but it should dry out after a while of driving  :twisted:)

be sure to keep the spray away from the fan area if you're that concerned, and possibly away from belt areas/alternator.

good idea on the vacuum pump... imo its better than a priming pump because it basically forces the pump to suck the fuel in.  and it will even tell you if you have a loose connection or a badly leaking pump (if the vacuum on the pump decreases and no fuel is being sucked in  :lol:)

[hipifreq]

When I swapped out the fuel lines for viton it didn't take long for the IP to pull fuel. Maybe 30 seconds of cranking on an old battery is all it took to get enough fuel to fire the engine. That's after having completely emptied the fuel lines. It seems to me that when you have a full tank and open up the lines enough, then gravity will push fuel through the lines to just below the fuel filter, and after that it's not much effort to pull the fuel through from there. Especially if you fill the filter with fuel before screwing it in.

[745 turbogreasel]

If you haven't got air in the injector pipes, you should prime in under 45 seconds  cranking with the wire pulled.I filled the If there is air in the pipes, loosen all the injector ends 1/2 turn, and crank(wire plugged in) till fuel begins to drip.  Tighten em down.
I did one a few days ago that had lost all fuel while parked a few months.
I filled the fuel filter, and IP from the inlet fitting with tranny fluid and WD40(what i had on hand).  
She fired right up with less than normal smoking according to the owner!

[TomB]

Aye, I'd say with a primed fuel filter, you'll give a a few seconds of running to start pumping some fuel though.  It'll die when it catches air of course, but shouldn't take longer than 30 secs odd to pull fuel through the lines.
Cheers,
Tom

[saurkraut]

You can also use a primer bulb, like the ones that go on out board motors.

I've found that pushing the fuel through the filter and into the pump gives a better prime especially with used pumps.  Drawing a vacuum on the return port is OK, but some used pumps prefer the"push" prime.

[mac.man25]

SHE LIVES! Well at least for 5-8 minutes before dieing. IT seems as though the fuel filter just is not giving up enough fuel for the engine to run. If I let it set for a few minutes I can start it again and it runs for a good amount before dieing again. If I just try and start it, it fires, but does not start.

I think I will try a new fuel filter and see if that clears it up. Would air in the fuel filter do something like that? It's almost acting as if vacuum is building up drawing fuel when the engine is off, but not drawing enough to actually run the engine.

Any ideas?

[745 turbogreasel]

That bis the symptom list for a plugged fuel fiter.

If it doesn't work:
(can)===hose==={filter}===#ENGINE#-|

[hipifreq]

My fuel filter got plugged with cold biodiesel recently, and that's the symptoms I had: would start and run fine for a minute or two, then would lose power and sputter. To get it home I had to shut off the engine and let it sit for a few minutes every 1/4 miles or so. Took a LONG time to get the 10 miles or so. After changing the fuel filter it ran just fine.

IMHO: What's happening is the fuel filter is partially plugged, but the pump still wants to get SOMETHING. That something becomes air from under the fuel filter o-ring. Once you shut down, the pressure is relaxed, and fuel left in the line replaces air in the pump with just enough to run for minute before choking again.

Is your filter-to-pump line clear or has it gotten so old it turned brown? I put a new nylon line in mine, and it lets me see any air coming through.

[mac.man25]

Is your filter-to-pump line clear or has it gotten so old it turned brown? I put a new nylon line in mine, and it lets me see any air coming through.

It's brown, and I think I will take your advice, just replace that line withsomething more see through.  I have already orderd a replacement filter, I just have to wait till tomorrow before I can pick it up.

Thanks.