1989 85HP FORCE FUEL PROBLEMS

[KRISFLORES94]

hi everyone I am new to the group and I have searched everywhere to try to find help with my problem.
I was given a 16.5' Quantum bass boat with the 85HP Force on it I had to replace the carpet and a few board and while I had it apart i cleaned the fuel tank best i could due to it had been sitting for 5 years. first time i took it out it ran great after some minor adjustments to the throttle linkage. the next time I went out i had a carb start leaking out of the over flow hole so loaded up took it home and cleaned the carbs(overflow due to trash in needle valve) changed fuel filters and line out as well. Reset the IAS to just a little over a turn out and got it running smooth but when i take it out it now runs fine for a maybe 2-3 mins at idle then dies and wont restart till i reprime the fuel system. At wot it runs great for about 15-25 secs then slowly dies. Replaced fuel pump diaphragm primer bulb and still had the same problem the next time i took it out. I know this is a big nono but i rigged up a electronic fuel pump for test purpose to see if was lack of fuel like i suspected and it ran great i just dont want to run that for safety reasons. I have a clear filter between the pump and carbs and at idle it barely drips fuel when in neutral giving a little rev it will fill the filter up but once dropped back down it sucks the filter dry so i am kinda at a loss here i feel like it might have a idle to low or something??

 

[Jiggz]

Great you have the clear filter between the pump and the carb. Obviously, the problem is a fuel delivery problem and not carburetion. If you have a portable tank (external tank) you next best troubleshooting should be to connect the inlet side for the fuel pump to the external tank using totally different set of hoses and primer bulb.

If the problem goes away, you know the problem is with the existing fuel hose, primer bulb, suction pipe or even the fuel tank vent. If the problem persists, then the only thing left to check is the fuel pump itself. Don't forget there is also the screen fuel filter on top of the fuel pump in addition to the inline clear fuel filter.

Lastly, check the plugs make sure they are all firing accordingly. If you suspect a plug not firing do a compression test on all cylinders.

 

[KRISFLORES94]

After work I will run compression on it just changed the plugs and wires on it and they all look the same no unusual signs of no spark or flooding condition. I will also test on muffs with a gas can and different line while there. I have a 24gal built in tank and I checked all of the vent lines disconnected and blew it out when replaceing the carpet I did this as well due to noticing dirt in it but did it again since i know mud dobbers are a problem. Also when I fill up you can feel/hear the air coming from the vent.

 

[Jiggz]

That is correct. A compression check will surely narrow the troubleshooting process. But with the clear fuel filter emptying it sure is a fuel delivery problem. But, since the fuel pump is operated through compression changes in the cylinder a low compression can actually affect its performance.

 

[KRISFLORES94]

ok so i ran a compression check and to my surprise for this old motor it has an even 140# on all 3 cylinders i noticed when i went to prim the fuel the bulb never got hard and fuel started running out of the lower unit? Diaphragm has a 1.5 inch slash through it so before I can do anything I have to get a new diaphragm.

 

[Jiggz]

There's your problem a torn diaphragm.

 

[KRISFLORES94]

so i got another diaphragm and after a squezze the primer twice it gets hard try and turn it over nothing comes out but filter going into the pump is now almost dry. took pump off and there goes another diaphragm am i doing something wrong or is there another problem?

 

[Jiggz]

No Title

This is what the fuel pump looks like. The three most important parts are listed. Make sure are all parts are properly arranged in the order as shown.

 

[Nordin]

Did the diaphragm got bad after you squeezed the bulb?

Disassemble the pump, check the diaphragm and the check valves. There is one at the inlet part of the pump and one at the outlet.
You can check the check valves by blowing and sucking at the inlet and outlet of the pump.
With the pump assembled with the diaphragm you sould be able to blow ion to the inlet but not suck and be able to suck in to the outlet but not blow.

 

[jerryjerry05]

Depending on where you bought the diaphragm????
​It could be 15-25 years old already???
​Chinese aftermarket can be new and bad right out of the package.

I try to save $$ but some parts need to be OEM.

​I installed a brush kit in a customers starter.
​It worked fine for the first 2 weeks.

​Guy calls and says "I" did something wrong. NOT!!

The wires coming from the brush came loose and wouldn't make contact.
Luckily I hadn't thrown away the stuff I took out.
​Replaced that and it still works years later. OEM

 

[Simple_Man]

I had a "new diaphragm" rip on the 2nd day. It happens.

 

[KRISFLORES94]

I will try that today when I get the new Diaphragm the first 2 I ordered from here the one Im supposed to get today is a 18-7806-1 sierra from oreillys so we will see.
I did disassemble the pump and checked the check valves and they seem to be ok but I will try blowing with the diaphragm in before installing it.
And yes the diaphragm tore during priming it let a little fuel through the pump into my carb filter but then the bulb got soft and fuel wasn't coming out of the pump instead it started coming out of the case

 

[Jiggz]

Well hopefully, the third will be a charm!

 

[KRISFLORES94]

Well I think that did it here's a video of the filters if I could get an opinion on if the flow looks right please

 

[Jiggz]

The clear fuel filter before the fuel pump is unnecessary. There is already a fuel filter on top of the fuel pump. Having this filter creates more load for the fuel pump meaning it increases the suction lift required to get fuel to the pump. However, this is all about personal choice. You can try to remove that fuel filter and experiment to see if fuel delivery can improve.

From the video it seems the fuel filter between the pump and carb is getting full. The final test will be on the water at WOT.

 

[jerryjerry05]

Like Jiggz said, the first filter isn't needed.
​But install a water/ fuel separating one in the system.
​It goes between the tank and the pump.
​It has an automotive type filter and not too much resistance.
The filter after the pump is right.

 

[KRISFLORES94]

I do not have a filter in the pump that is why I put the one before(well the previous owner did) I just replaced it and it does assist with seeing fuel flow. And as for fuel level after the pump before the lower filter would suck dry at idle now it's not so I guess the only way to find out now is a trip to the lake

 

[Jiggz]

You may not be aware of it because it is not readily seen. But if you look back at the diagram part #4 is actually called fuel screen which is located on top of the fuel pump. And yes, that is considered a fuel filter. Like, I said, it is a personal choice if you want to keep the first filter. Goodluck on your op-test.

 

[KRISFLORES94]

I know as the other boat in the video has an 88 85hp Force and it has one on it. Just put a new started on that one too

 

[KRISFLORES94]

ok so I got it back out on the water today and now it has fuel but now when i put it in gear it stalls out even if i turn the idle up, just dies and its only in forward in reverse it will be fine but not forward any ideas? there is a little back fire here and there after it dies when restarting feel like it is flooding out but in nutral it revs fine