Rebuilt tandem pump, now no start. Priming it...?

[black_slug]

So I installed a new seal and gasket set on my tandem pump.

I removed the battery to give myself more room (installed a new coolant flange as well).

I initially thought I must have done something wrong when disconnecting or connecting it because it won't start now.

Now I've learned the pump needs to be primed, which makes sense.

Here's a video of me attempting to start it. Going to try and start it a few times today but I've heard you need to do it like 20, 30, 40 times consecutively, which makes me a little nervous.

https://photos.app.goo.gl/gZywAEWCwiTVYqdu7

Thoughts?


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[black_slug]

I was thinking the whirring sound is the starter spinning but not being engaged by the solenoid. Might replace the starter but still not sure about the whole priming the tandem pump aspect. Thoughts anyone?

Probably gonna bring my battery and starter in sometime this week to have them tested. I actually replaced a starter once that passed the bench test at O'Reilly's but still turned out to be the problem, so I'm a bit apprehensive about replacing a starter when I have the whole tandem pump dilemma.

Happy Sunday everyone!

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[Mike_04GolfTDI]

You don’t exactly need to prime the tandem pump. The electric pump in the tank will take care of that, unless it doesn’t work.

Air in the injectors is of more concern. To get the air out more quickly, remove the glowplugs and crank the engine until diesel mist comes out of the glowplug holes. Then put the glowplugs back and it should fire right up.

Pumping against the pressure in the cylinder, the injectors can’t force much air through because it just compresses and uncompresses without really going anywhere. With glowplugs removed, there’s just atmospheric pressure to work against, instead of over 400 psi.

 

[black_slug]

Ok. So remove glow plugs from cylinders put leave inline/connected electrically? New to deisel so bot sure about how the fuel delivery/ignition system works. I'll try that.

Still think it could be the starter though? I'm thinking that could be an issue now as well since it looks original and the wiring hasn't moved since day one of it's life (I had to remove the solenoid to retrieve a socket I dropped, then reinstalled just how it was). The starter seems to be spinning but not sliding into and engaging the flywheel.

Thanks for the help. I'll look into the glow plug thing.

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[black_slug]

You don’t exactly need to prime the tandem pump. The electric pump in the tank will take care of that, unless it doesn’t work.

Air in the injectors is of more concern. To get the air out more quickly, remove the glowplugs and crank the engine until diesel mist comes out of the glowplug holes. Then put the glowplugs back and it should fire right up.

Pumping against the pressure in the cylinder, the injectors can’t force much air through because it just compresses and uncompresses without really going anywhere. With glowplugs removed, there’s just atmospheric pressure to work against, instead of over 400 psi.

Piggybacking on my last post, so you should see a 'mist' coming out of the glow plugs, not the injectors?

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[Mike_04GolfTDI]

With the glowplugs removed, fuel and air will come out of the holes that the glowplugs were in.

The injectors are under the valve cover where you can’t see them, and they inject fuel directly into the cylinder.

Your video didn’t work for me, but from what you describe it seems like your engine isn’t even turning over? You’d need to correct that situation before you even need to think about the fuel system. Based on the title I figured this was mostly a post about the tandem pump.

When you try to start it, if the engine isn’t cranking, then I guess something is wrong with your starter. If it worked before you rebuilt the tandem pump then maybe you just disconnected a wire accidentally or something. Hope it’s nothing too serious.

Since the tandem pump is driven by the cam, I guess there’s a small possibility that if the tandem pump is stuck and not spinning then maybe the engine won’t turn when you try to start it. I’m not sure what would happen in that scenario. Best case would be the starter isn’t powerful enough to do anything, otherwise something would break. I only suggest this because you rebuilt the tandem pump.

So one thing you might want to do is ensure that the engine can turn over. If you have a manual transmission then this is easy. Just put it in 2nd or 3rd gear and push it forward and see if the engine turns. Remove the glowplugs or unplug the injector wiring harness so the engine can’t start and run you over while doing this. If it’s automatic then I guess you have to get a socket wrench on the large bolt in the center of the crank sprocket and turn it over that way.

 

[black_slug]

With the glowplugs removed, fuel and air will come out of the holes that the glowplugs were in.

The injectors are under the valve cover where you can’t see them, and they inject fuel directly into the cylinder.

Your video didn’t work for me, but from what you describe it seems like your engine isn’t even turning over? You’d need to correct that situation before you even need to think about the fuel system. Based on the title I figured this was mostly a post about the tandem pump.

When you try to start it, if the engine isn’t cranking, then I guess something is wrong with your starter. If it worked before you rebuilt the tandem pump then maybe you just disconnected a wire accidentally or something. Hope it’s nothing too serious.

Since the tandem pump is driven by the cam, I guess there’s a small possibility that if the tandem pump is stuck and not spinning then maybe the engine won’t turn when you try to start it. I’m not sure what would happen in that scenario. Best case would be the starter isn’t powerful enough to do anything, otherwise something would break. I only suggest this because you rebuilt the tandem pump.

So one thing you might want to do is ensure that the engine can turn over. If you have a manual transmission then this is easy. Just put it in 2nd or 3rd gear and push it forward and see if the engine turns. Remove the glowplugs or unplug the injector wiring harness so the engine can’t start and run you over while doing this. If it’s automatic then I guess you have to get a socket wrench on the large bolt in the center of the crank sprocket and turn it over that way.

I didn't disconnect anything other than the battery, wire/cable wise.

I'm gonna take it in with my battery and test them I think. I have replaced a starter that PASSED a bench test before, as there weren't really any other viable culprits.

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[BobnOH]

Starter and battery should be self evident, it just needs to turn a certain RPM (400?). Purge the air, it should start.

 

[black_slug]

Starter and battery should be self evident, it just needs to turn a certain RPM (400?). Purge the air, it should start.

Is this done by removing the glow plug harness/rail? Should I pop the outlet off the pump and purge it into a container of some sort? Or just the glow plug thing?

Sorry, kinda inexperienced. Thanks for the tips!



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[black_slug]

Is this done by removing the glow plug harness/rail? Should I pop the outlet off the pump and purge it into a container of some sort? Or just the glow plug thing?

Sorry, kinda inexperienced. Thanks for the tips!



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My only other concern is just the fact that I hear the starter spinning (I think that's the whirring sound I hear) but not engaging the flywheel. I had to unbolt the solenoid from the starter assembly to get a socket that fell behind it. Maybe I muffed it up putting it back--though I rechecked it and reinstalled it again the same way I saw it when I first took it off.

I want to try the purging of the air and/or priming of the system first but just wanna make sure I do it correctly.

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[Vince Waldon]

I hear the starter spinning (I think that's the whirring sound I hear) but not engaging the flywheel. I had to unbolt the solenoid from the starter assembly to get a socket that fell behind it.

If that's what you hear that's probably what is happening... you could have someone watch the belts at the front of the engine to see if the crank is actually moving or not.

If you're not actually turning the engine over that needs to be fixed first before you can see if it will prime or not.

 

[black_slug]

If that's what you hear that's probably what is happening... you could have someone watch the belts at the front of the engine to see if the crank is actually moving or not.



If you're not actually turning the engine over that needs to be fixed first before you can see if it will prime or not.

Ok. Hmmm. Maybe I'll just eat the 200 and put in a new starter. That way I don't have to worry about a starter ever again (shouldn't have said that) and I can focus my energy elsewhere...or it starts!

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[BobnOH]

Is this done by removing the glow plug harness/rail? Should I pop the outlet off the pump and purge it into a container of some sort? Or just the glow plug thing?

Sorry, kinda inexperienced. Thanks for the tips!



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Well it sounds like you just have a starter issue. But if you do end needing to purge, the process described (I don't know the PD) is to simply remove glow plugs and crank til you get a mist out the hole.

 

[black_slug]

Well it sounds like you just have a starter issue. But if you do end needing to purge, the process described (I don't know the PD) is to simply remove glow plugs and crank til you get a mist out the hole.

So essentially remove the harness like this? The glow plugs come out with it naturally I suppose...? Sorry, new to diesels.

Obviously I know I'd keep it connected electrically.
https://r.tapatalk.com/shareLink/to...0&share_fid=6491&share_type=t&link_source=app

Local vendor had the wrong starter in stock so gonna try this and have my buddy look at it so I have a second set of eyes.


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[black_slug]

After some fiddling around and rechecking things, I'm 90%+ certain it's the starter solenoid. I must have ****ed it up somehow by taking it off/apart from starter assy.

Popped off a fuel line and sure enough fuel came rushing out so I quickly put it back in place.

Gonna have a buddy give me a second set of eyes at some point (he's smarter/more knowledgeable than me).

Now to decide to get just a solenoid or the while assy...?


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