Volvo Penta 5.0 GLPWTR accelerator pump question

[Augoose]

I've got a '99 VP 5.0 GLPWTR. I've rebuilt the carb but noticed that the replacement accelerator pump diaphragm which came in the Sierra kit model 18-7238 is much smaller than the one that came out. According to Amazon, 18-7238 cross references to VP part # 3854020/OMC 986796. According to the VPstore site, #3854020 is the appropriate kit for my boat.

Here is a photo of the two diaphragms - the black one is the old one, the green one is the new one.


Thanks!

 

[alldodge]

Agree, Your motor comes up with 3854020 which crosses to Sierra 18-7238
I have no info as if Sierra parts have any quality control

There is a good possibility that the carb on your motor was changed at some point. Look on the body of the carb for a number

 

[Augoose]

Thanks AllDodge. Good points on the quality control and possibly a change in the carb itself. I'll take a look at the carb and report back.

 

[Augoose]

My carb has 3858334, 75004-1, and 2008 on the casting. On the VPStore, 3858335 was the original rebuild kit part number,- one digit away from my casting #. Anyone know of a good part cross-reference site?

 

[Lou C]

that is a Holley carb, you need to find out the Holley model number and there is also another # on the air horn, you can look on the Holley website and get the rebuild kit directly from them....

it is a Holley 2bbl, they made a 300 cfm version (part # 08320-1) and a 500 cfm version (part # 80402-1) you have to figure out which one was used on the your engine, Holley site indicates that the 300 cfm was used on Ford 302s but not sure if that is true for a GM 5.0 which is what you have....

https://www.holley.com/products/fuel.../rebuild_kits/
try using this link to figure out which holley kit you need, scroll down to how to id your carburetor.....
watch the vid

 

[Augoose]

So I watched the video and my list # is 75004-1. I looked up my service manual and according to that, my list should be R-75004A. So, it seems my carb is the original one. The downside is that I searched this list # all over on Holley's website and found that it wasn't helpful at all. I did see in the service manual that stock settings for the power valve was a 4.5 and the main jets were 69's - so that was helpful as the PV that came with my sierra kit was a 6.5 and it was missing the umbrella check valve too. Not impressed but I suppose that's what I get for not ordering a Holley kit.

My original accelerator pump diaphragm seemed to check out fine so I'm going to reuse it.

If I end up locating the proper Holley rebuild kit for my application I'll post it.

 

[alldodge]

Member Augoose has/had the same carb (post 5 from March 2012)

he numbers on my carb were 3858334, 75004-1 which is the "list" number, and 2208 which I'm told by Holley is the date. When I called Holley, they told me the rebuild kit for list 75004-1 is the 703-36.

https://forums.iboats.com/forum/eng...vo-penta-5-0gl-pwtr-acceleration-bogging-dies

 

[Lou C]

I have found this same frustration with looking things up on the Holley site, it does pay to call them even if they keep you waiting on the phone. Looks like from the above you need the 703-36 kit.

 

[Lou C]

https://www.holley.com/products/fue...ts/rebuild_kits/marine_renew_kit/parts/703-36

 

[Augoose]

Member Augoose has/had the same carb (post 5 from March 2012)



https://forums.iboats.com/forum/engi...n-bogging-dies

Thanks AllDodge.
Embarrassingly, that's my post from the last time I rebuilt this carb in 2012. I searched and searched for that thread and couldn't find it nor could I replicate the internet searches that led me to that Holley kit last time. Seems I called them. Good thing my memory isn't slipping...doesn't help that I've got more gas engines around me than leaves on trees and one carb experience seems to flow right into the next one.

What is interesting however is that the 703-36 kit included a 6.5 power valve while the service manual calls for a 4.5.

Does anyone have an opinion on which power valve I should go with?

 

[alldodge]

Thanks AllDodge.
Embarrassingly, that's my post from the last time I rebuilt this carb in 2012. I searched and searched for that thread and couldn't find it nor could I replicate the internet searches that led me to that Holley kit last time. Seems I called them. Good thing my memory isn't slipping...doesn't help that I've got more gas engines around me than leaves on trees and one carb experience seems to flow right into the next one.

What is interesting however is that the 703-36 kit included a 6.5 power valve while the service manual calls for a 4.5.

Does anyone have an opinion on which power valve I should go with?

Man I'm getting old or something, I read the question but not paying much attention to who post the question :facepalm:

This is for a car but should work for the boat. It says to take a vacuum reading at idle, then divide the reading by 2, and that is the size PV you need. Guess the good part is a PV is easy to change out

https://www.holley.com/blog/post/holley_power_valve_tuning/

 

[alldodge]

Just read something which should help. The lower the number the lower the amount of fuel is given. So a 4.5 can be great for a car on the flat road, but a boat or a truck pulling a hill would need a larger one like the 6.5

Could be you should use the 6.5 because more fuel. More fuel is better in a boat and if it turns out the pulgs are showing to rich, can then lean it out some

The first place to start power valve tuning is to choose when this valve should open. Choosing a lower manifold rating (like 4.5 InHg) delays the onset of additional fuel. This might work on a street car with a deep gear and a loose converter for example. Where the power valve opening point might be more critical is in a towing situation where a long climb up a steep grade would demand more fuel to ensure the engine does not run too lean. In this case, an 8.5 InHg power valve might be a better choice. Each situation and engine will require a specific tuning application.

https://www.enginelabs.com/engine-t...s-holley-power-valves-explanation-and-tuning/

 

[Lou C]

The # on the PV is the inches of mercury reading of manifold vacuum when the PV starts to open. So a 6.5 would open at a smaller throttle opening level that a 4.5. What one was in it before and what did your plugs look like? If running rich try the 4.5 if lean try the 6.5...

 

[Augoose]

Thanks again gentlemen. I don't know what came in the carb before 2012 as I just blindly put the 6.5 that came in the Holley kit and went with it, tossing what came out in the trash.

'll say that the boat has always run well since 2012, maybe not as much hole shot as I would have liked, but there's a whole lot that goes into that that we won't cover here of course.

The boat is not running currently so I can't verify what my vacuum is right now, so I suppose I'll go with the 4.5 cited in the service manual and see if it runs better than what I'm used to. Plugs always looked good upon inspection- not lean or rich. Like mentioned above, its quick work to swap back to the 6.5 if its worse. I suspect I'll be better off with the 6.5 for reasons mentioned above but who knows. My jets are still the stock #69's too.

Thanks for the background info on measuring power valve sizes as well.

For anyone else buying these kits and in summary, the Sierra kit (18-7238) was $15 more expensive than the Holley kit (703-36), and the Sierra kit did not come with an umbrella check valve, the correct accelerator pump diaphragm, or the correct power valve (according to the SM). The Holley kit I bought in 2012 also came with the blue rubber gaskets while the Sierra kit came with the traditional paper and cork gaskets.

I've ordered a new Holley kit and in the image it seems to come with a 4.5 power valve now despite arriving with a 6.5 back in 2012. We'll see what comes this time.

Thanks for the assistance!

 

[alldodge]

Plugs always looked good upon inspection- not lean or rich.

Plugs look good and you have the 6.5 in now, suggest leaving the 6.5 because the 4.5 just makes fuel lean out.

 

[Augoose]

Plugs look good and you have the 6.5 in now, suggest leaving the 6.5 because the 4.5 just makes fuel lean out.

Makes sense, thanks Sir!

 

[Scott Danforth]

30cc diaphragm on left, 50cc diaphragm on right.

you need the 30cc unless you have a big-block set up for drag racing

 

[Augoose]

......30cc diaphragm on left, 50cc diaphragm on right.

you need the 30cc unless you have a big-block set up for drag racing

Interesting. I tried to research what size accelerator pump diaphragm I should be using and read that the diaphragm should fill up the housing. The 30cc didn't come close and it would have required a serious adjustment to the linkage for it to deliver a shot at the appropriate time, and the linkage arm would have been up inside the accelerator pump housing pretty far to make contact with the post on the 30cc. Not knowing which one to use, I kept the 50cc and installed it today. Should I pull it out and put in the 30cc?

Update with how it runs below...

 

[Augoose]

So I installed the carb today. In total, I replaced the coil, cleaned the pickup sensor on the ignition module, replaced all the spark plugs, replaced the distributor cap and rotor, new water fuel separator, pumped out all the old fuel, installed a new alternator, and replaced the fuel pump relay.

At the end of the season last year I replaced the starter as it failed when I unknowingly hydrolocked the engine when it stalled while underway.

The connections at the coil were all rusted as well and several of the posts on the old alternator just spun when I tried to remove connections. I also checked the connections at the ignition key and did find that I could tighten each just a bit, especially the purple wire.

Here was the old fuel relay.


I put about 15 gallons in the boat and started it up in the yard. It ran very well and needed just a quarter turn on each fuel screw to about 1 full turn out. Revved up nicely w/out load of course. Tomorrow I plan to water test it at the dock for a bit and then maybe wander around the cover without getting too far out to test things. The original problem was that the boat would just die completely while under way. No cough, no sputter, just stopped. Didn't seem to ever happen at lower rpms or at idle that I can recall.

Hopefully one of the steps above resolved it.
Thanks all for the assistance.