Acceleration Pump Oulet Check Valve Failures

[LSaupe]

Greetings all:

I have a 97 Challenger 787 that I have been having acceleration pump problems with.

I purchased this boat used. It runs fine other than the acceleration pump was intermittant (or usually didnt work at all - requiring quick stabs of the choke to get it up to mid range RPM).

I inspected the pump and found the outlet check valve to have falied. I cleaned it several times, but it would work intermittantly at best.

I finally gave up bought a new OEM pump (big $$$). This worked great for a weekend but is now doing the same thing!

To verify what was going on I replaced the rubber 1/8" primer lines with clear. When the pump activates it pulls from both directions, effectively providing little benefit. Sometimes it does work, but it is intermittant.

The carbs have been cleaned several times and new filters and fuel lines installed but I still have this issue. Everything is squeaky clean.

Any idea what to do here, or have any of you run across this before? Could both pumps have been defective? The pump I replaced also looked like a new one (not painted like the carbs and very clean - like this problem was addressed once before). Unfortunately this boat was confiscated and resold by the DEA so I have no one to contact on its maintenance history.

I am thinking of installing an external chack valve downsteam of the pump. Anyone know of a vendor for a 1/8" barbed check valve?

Larry S,

 

[97 See Doooo]

What about a little pressure check valve thats in a widshield washer pump line on a car ??? just a thought . . . and im kinda haveing the same problem . . also, is 75 buck a good price for a new excelerator pump?? anyone

 

[LSaupe]

I paid $235.00 for mine. And that was one of the cheaper listings. Need to be cautious of the plastic pumps (to ensure compatibility with fuel). Also, not to sure of the output pressure from the pump but am guessing it is at least 5-10 PSI, maybe more.

 

[Jetson]

How did it turn out?

I am having a problem that sounds a lot like that! Just wondering how it all turned out?

 

[LSaupe]

I am currently on the road (down in Boston).

I am going to order a check valve from McMaster Carr before I head back. If it works I will post the results and part numbers. Can get a nice valve (with low unseat pressure) and fitting for 1/8" hose barb for about $30.00.

 

[LSaupe]

Just had the boat out last night, the check valve worked but I am still pulling some air from the carb bowl for some reason. So I am half way there.

I chose a low pop off pressure spring loaded check valve (1/3 psi) with Buna N seal. About $12.00 from McMaster Carr.

I got the check valve, two 1/8" NPT elbows and a pack of 1/8" NPT to 1/8" hose barb adapters.

I used the elbows because I thought it would be too tight for a straight run. Turns out it probably could have worked fine without the elbows (though you would need to select a female check valve in lieu of the male).

Anyway, here are the part numbers to what I used:

Valve (1) : 7775K21 (the female pert is listed right next to it should you prefer that one)

Elbow (2) : 50785K35

Barb Hose Adapter (2, though they come in a pack unfortunately): 5346K61

Larry

 

[LSaupe]

Here is a further update.

I initially installed this with the flow pointed down (inlet at the top and outlet at the bottom). I ran into a problem where, due to its increased diameter, it could not effectively purge air bubbles (it would collect in the elbow and inlet section of the valve). The small 1/8" line forces bubbles straight through, but the larger diameter valve collects them. The fix was to have the flow go up through the valve (inlet at the bottom and outlet at the top).

Purges through fine now. Live and learn I guess.

Larry S.

 

[LSaupe]

Made a modification to the assembly to lessen any places for air to form.

I basically turned down the NPT to hose barb fitting and cut 5/16-24 male threads on it. Then drilled and tapped the valve for female 5/16-24 threads.

Went together great. I sealed the threads with epoxy just to be sure.

Nice small system now. Before and after Pic attached.