Carb Rebuild and New OEM Fuel Pump Install

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bbolander
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Carb Rebuild and New OEM Fuel Pump Install

Post by bbolander » Mon Apr 24, 2017 11:14 pm

We just completed what we thought was a successful Zenith 36NDIX carburetor rebuild and SAV OEM fuel pump install. As covered in separate threads, we were having fuel in the engine oil, gas dripping in one carb when running and after running, a very high float level in the rear carb, gas smell, exhaust smoke and smell, and power loss on grades.

Since the fuel was drained from all the fuel lines and the SAV OEM pump seemed stiff, we had trouble at first getting fuel for starting. We took the pump off and manually pushed the lever several times, used a vacuum pump to help suck fuel into it, and then it worked.

We've only tested it after the rebuild in the garage so far. But it runs very smooth, both float levels are perfect (two 1 mm washer on each float valve), synchronization is very good at 10 for both carbs. And there is no exhaust smoke or smell.

We've had a lot of help from folks on this forum, thanks so much!

https://youtu.be/VTGw-Jwe9EI
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Last edited by bbolander on Sun Apr 30, 2017 4:55 pm, edited 1 time in total.
1971 Pinzgauer 710M, all stock including 245-16 Maloya tires, taken off and stored for show
BFG MT KM2 265/75R16's on Black SAV replacement rims on now

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TechMOGogy
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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by TechMOGogy » Tue Apr 25, 2017 8:31 am

Just wondering why you have 5 separate threads about your carbs?
It may be easier to just have a 'Rebuilding Carbs' thread and then post all carb related questions/issues there?
Just an observation
72 Pathfinder | 75 710M 2.7i | 94 350GDT | 96 350GDT Worker

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bbolander
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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by bbolander » Tue Apr 25, 2017 8:47 am

TechMOGogy wrote:Just wondering why you have 5 separate threads about your carbs?
It may be easier to just have a 'Rebuilding Carbs' thread and then post all carb related questions/issues there?
Just an observation
Yes, in hindsight that would have been better. I'll keep that in mind next time. But as we were going through it we had different immediate problems that we needed input on.

We did notice a fuel seep from each carburetor at a welded plug on the top plate. We'd appreciate input on how to seal those leaks here:

viewtopic.php?f=12&t=10917
1971 Pinzgauer 710M, all stock including 245-16 Maloya tires, taken off and stored for show
BFG MT KM2 265/75R16's on Black SAV replacement rims on now

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bbolander
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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by bbolander » Wed Apr 26, 2017 10:29 pm

Well, the carbs at idle were great, idle mixture screws 2 turns out and reading 10 on the syncrometer.

But we have a bog down flat hesitation off of idle, like we've seen several threads about. We have to feather the gas pedal to get the rpm's up to move. After that there's plenty of power.

We're going to check vacuum and play with the idle mixture and idle speed like others have done to see if that helps.

We're at 5600 ft elevation now, where for the last 7 years the Pinz has been at 1000 ft. We want to advance the timing a couple of degrees, but we have the PinzSSI system and can't find how to advance the timing with it. Do we turn the distributor shaft like would be done before the PinzSSI?

We noticed that the accelerator pump fuel kind of tumbled out of the nozzles when we pressed the gas pedal, which seems unusual since our other old carburetors have a strong stream. The SAV kit didn't come with a new pump upstroke or pump pressure valve so we used the old ones. The check balls in them rattled freely. So we're wondering if the check balls aren't functioning correctly to make the accelerator pump provide a strong fuel stream. Could these two valves be bad? I just ordered new valves just in case. Or is the tumbling stream normal for these carburetors?

Any help on the timing adjustment method with the PinzSSI and the accelerator pump questions will be appreciated.
Last edited by bbolander on Wed Apr 26, 2017 10:58 pm, edited 2 times in total.
1971 Pinzgauer 710M, all stock including 245-16 Maloya tires, taken off and stored for show
BFG MT KM2 265/75R16's on Black SAV replacement rims on now

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Jimm391730
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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by Jimm391730 » Wed Apr 26, 2017 10:40 pm

I've found that the Pinz really needs a big accelerator pump flow to prevent stumbling, but also needs a strong spark. I had a stumble with the old stock ignition, but mostly disappeared going to the Civi ignition. But you shouldn't worry with the SSI kit. You can advance the SSI by rotating the disk a bit clockwise, further than what triggered the red LED when you set it up. Remember, the dizzy shaft runs at half the speed of the crank, so 5 degrees of SSI disk rotation clockwise beyond the light equals 10 degrees of timing advance.

Vacuum does nothing, except to slowly dry out the factory dizzy. No vacuum advance so as long as you don't have any intake vacuum leaks you should be good.
Jim M.
712W and 710M

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bbolander
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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by bbolander » Wed Apr 26, 2017 10:51 pm

Jimm391730 wrote:I've found that the Pinz really needs a big accelerator pump flow to prevent stumbling, but also needs a strong spark. I had a stumble with the old stock ignition, but mostly disappeared going to the Civi ignition. But you shouldn't worry with the SSI kit. You can advance the SSI by rotating the disk a bit clockwise, further than what triggered the red LED when you set it up. Remember, the dizzy shaft runs at half the speed of the crank, so 5 degrees of SSI disk rotation clockwise beyond the light equals 10 degrees of timing advance.

Vacuum does nothing, except to slowly dry out the factory dizzy. No vacuum advance so as long as you don't have any intake vacuum leaks you should be good.
Thanks Jimm. Our previous Owner had the SSI put in so all we have are the instructions. So we remove the SSI cap and rotate the disc clockwise until we read another 2 degrees with our timing light on the v-belt pulley mark, correct?. Will we see another red LED light or is that just the initial setup position?

Sorry, I didn't mean check for vacuum advance. I mean't check for vacuum leaks. We put in a new inlet manifold balancing hose and new inlet manifold gaskets along with the carb rebuild. We still have the old power booster vacuum hose and check valve but I ordered new ones tonight just in case. We just need to check to see that there isn't a vacuum leak somewhere.
1971 Pinzgauer 710M, all stock including 245-16 Maloya tires, taken off and stored for show
BFG MT KM2 265/75R16's on Black SAV replacement rims on now

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Jimm391730
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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by Jimm391730 » Wed Apr 26, 2017 11:14 pm

We just need to check to see that there isn't a vacuum leak somewhere.
You'd probably have a high idle with any significant intake (vacuum) leaks.
So we remove the SSI cap and rotate the disc clockwise until we read another 2 degrees with our timing light on the v-belt pulley mark, correct?. Will we see another red LED light or is that just the initial setup position?
The instructions (IIRC) say to line up the timing pointer with the mark on the crank pulley (TDC) then loosen the SSI disk and slowly turn it clockwise just until the LED lights, then tighten the screw. This should be the initial setup. If you want additional advance, rotate the disk a bit further clockwise (remember the 1:2 degree relationship). If its running OK and you just want a bit more advance there is no need to line everything up IF you just move the disk a smidge further clockwise, but if you slip you won't know where you should be - then you have to get it all lined up to get it reset. But if you line up the pointer first, you will ensure you have the #1 cylinder at the compression point and not between exhaust and intake point (line up the pointer in the area where the LED comes on and not 360 degrees away). Now if you slip, you can get it set back correctly.
Jim M.
712W and 710M

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bbolander
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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by bbolander » Thu Apr 27, 2017 4:55 pm

Jimm391730 wrote:
We just need to check to see that there isn't a vacuum leak somewhere.
You'd probably have a high idle with any significant intake (vacuum) leaks.
So we remove the SSI cap and rotate the disc clockwise until we read another 2 degrees with our timing light on the v-belt pulley mark, correct?. Will we see another red LED light or is that just the initial setup position?
The instructions (IIRC) say to line up the timing pointer with the mark on the crank pulley (TDC) then loosen the SSI disk and slowly turn it clockwise just until the LED lights, then tighten the screw. This should be the initial setup. If you want additional advance, rotate the disk a bit further clockwise (remember the 1:2 degree relationship). If its running OK and you just want a bit more advance there is no need to line everything up IF you just move the disk a smidge further clockwise, but if you slip you won't know where you should be - then you have to get it all lined up to get it reset. But if you line up the pointer first, you will ensure you have the #1 cylinder at the compression point and not between exhaust and intake point (line up the pointer in the area where the LED comes on and not 360 degrees away). Now if you slip, you can get it set back correctly.
Do we advance the timing by rotating the disk with the engine off, engine on, or does it matter?
1971 Pinzgauer 710M, all stock including 245-16 Maloya tires, taken off and stored for show
BFG MT KM2 265/75R16's on Black SAV replacement rims on now

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Jimm391730
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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by Jimm391730 » Thu Apr 27, 2017 8:37 pm

Do we advance the timing by rotating the disk with the engine off, engine on, or does it matter?
The disk spins with the engine, but at half the crank rpms. So if you can adjust the disk when it is spinning at 4-500 rpm you will have my amazement! :shock: :shock: :shock: :lol:

Of course you have to stop the engine to loosen the screw, move the disk a smidge, and tighten the screw... you'll see!

On the other hand, if you loosen the dizzy clamp you can rotate the dizzy housing while the engine is running. In this case, you are rotating the "base" or "reference" to which the spinning disk is compared to. Its like moving the finish line of a race closer or further from the start; you can do this even while the runners are running. In comparison, adjusting the disk is like moving a runner 20 feet ahead or behind where they were - this is not (realistically) possible. But moving the "base" or "reference" has the opposite effect of moving the disk - to advance the timing, you will rotate the housing counter-clockwise (like moving the finish line closer to the start); clock wise rotation means the disk has to rotate further to get to the reference point which retards the spark (it takes longer to get to the reference point). This is the way that ignition timing has always been adjusted, by changing the "reference" point.
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712W and 710M

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bbolander
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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by bbolander » Fri Apr 28, 2017 10:44 am

Jimm391730 wrote:
Do we advance the timing by rotating the disk with the engine off, engine on, or does it matter?
The disk spins with the engine, but at half the crank rpms. So if you can adjust the disk when it is spinning at 4-500 rpm you will have my amazement! :shock: :shock: :shock: :lol:

Of course you have to stop the engine to loosen the screw, move the disk a smidge, and tighten the screw... you'll see!

On the other hand, if you loosen the dizzy clamp you can rotate the dizzy housing while the engine is running. In this case, you are rotating the "base" or "reference" to which the spinning disk is compared to. Its like moving the finish line of a race closer or further from the start; you can do this even while the runners are running. In comparison, adjusting the disk is like moving a runner 20 feet ahead or behind where they were - this is not (realistically) possible. But moving the "base" or "reference" has the opposite effect of moving the disk - to advance the timing, you will rotate the housing counter-clockwise (like moving the finish line closer to the start); clock wise rotation means the disk has to rotate further to get to the reference point which retards the spark (it takes longer to get to the reference point). This is the way that ignition timing has always been adjusted, by changing the "reference" point.
Ha Ha! What a great response Jimm!!! If I end up whirling around hanging on to the disk at 500 rpm I'll post the video!

We had no info on whether the disk turned or not. Glad to have your input, we know what to do now!
1971 Pinzgauer 710M, all stock including 245-16 Maloya tires, taken off and stored for show
BFG MT KM2 265/75R16's on Black SAV replacement rims on now

one2many
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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by one2many » Fri Apr 28, 2017 11:49 pm

When you rebuilt your carbs did you bush your throttle bodies (TB) or use the oversized shafts that are available?

If you have excessive play in the throttle shafts your engine will not only be sucking air past but you can also get a misalignment of the throttle plates when you accelerate as the shaft "moves around" to take up the play.

It can be difficult to determine excessive play of the shafts in the TB's while the carbs are mounted but one method is to spray some carb cleaner on the outside of the TB where the shaft exits with the engine running at idle, if your TB's are in good condition your idle will stay pretty stable when you do this. If your engine stumbles a little or the revs lift for a short period then the engine has sucked the carb cleaner through the worn TB indicating excessive wear.
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bbolander
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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by bbolander » Sat Apr 29, 2017 12:48 am

What kind of accelerator pump nozzle flow should we see? Should it be a tumble like we're seeing, or a strong sharp stream or strong spray?
1971 Pinzgauer 710M, all stock including 245-16 Maloya tires, taken off and stored for show
BFG MT KM2 265/75R16's on Black SAV replacement rims on now

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bbolander
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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by bbolander » Sat Apr 29, 2017 11:26 pm

Here is the best I could do today on a couple of videos of the bogging down and weak accelerator pump spray without someone else holding the flashlight. Any comments?

https://www.youtube.com/watch?v=R-_GKMqxGYw

https://www.youtube.com/watch?v=SolKibfbPo4
1971 Pinzgauer 710M, all stock including 245-16 Maloya tires, taken off and stored for show
BFG MT KM2 265/75R16's on Black SAV replacement rims on now

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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by audiocontr » Sun Apr 30, 2017 4:46 am

Weak stream equal across the carbs, or does one perform fine while one is problematic?
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bbolander
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Re: Successful Carb Rebuild and New OEM Fuel Pump Install

Post by bbolander » Sun Apr 30, 2017 6:29 am

audiocontr wrote:Weak stream equal across the carbs, or does one perform fine while one is problematic?
That's a good question. It seems like both but we haven't tried to operate with just one (that doesn't seem like a good thing to do though).

The accelerator pump nozzle flow is weak - all nozzles, both carbs. Now I can also see in the 2nd video that the fuel hose from the pump to the rear carb vibrates a lot when the gas pedal is pressed and the stumble occurs. The fuel pump is SAV OEM new. The new fuel lines are the correct SAV 5 mm lines.

The Pinz runs very strong after it gets past the coming off of idle stumble.
1971 Pinzgauer 710M, all stock including 245-16 Maloya tires, taken off and stored for show
BFG MT KM2 265/75R16's on Black SAV replacement rims on now

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