90 SPL wont run high rpm after bowls empty

[toddschubert]

After dealing with primer pump malfunction that was dumping fuel into carbs, I now have an issue where the engine runs after pumping bulb but shuts down after a few seconds. It will Idle all day and run high speed for a few seconds after idling. It seems that after the fuel in the carburetor bowls runs out it ceases to run properly. I had disassembled the fuel pump and noticed the diaphragm is badly warped or cupped.
There is no restriction in the fuel line as you will run out simply by siphon.
Am I correct in assuming I have a fuel pump issue and probably need to rebuild it?

 

[jakedaawg]

yep. To verify you could unhook the fuel out line at pump and crank engine over with the safety lanyard pulled out. If weak fuel flow rebuild pump, if really squirts look elsewhere for issue.

 

[racerone]

The primer unit is NOT a pump.-------Replace the cupped piece in the fuel pump and see what happens.

 

[flyingscott]

Simple to diagnose pump the primer ball on the fuel line when it is idling if it keeps running the fuel pump. But while it's apart change the diaphragm.

 

[Fed]

Looking at your other thread I think you never used the primer solenoid because it was leaking so was in constant use anyway and probably causing you running problems.
Now that you have it blocked off you will have starting problems and it will be difficult to keep it running by bumping the key until it warms up.

Racerone has said it a few times... IT'S NOT A PUMP. It's an electrically operated solenoid valve that is activated by pushing the key in.

I would reinstate a working primer solenoid then go from there. (Learn the operation of it including the red lever)

 

[jakedaawg]

Folks, he is now talking about the FUEL pump.


Todd, you will be fine if you follow what I said in post #2

 

[flyingscott]

The only thing I would say about taking the fuel line off and checking the pump besides having gas run all over. The diaphragm may test good when it's not because there is no pressure in the line. The pump has to work harder if there is pressure in the line and keep up with the carbs. If you disconnect the fuel pump it doesn't have to do any work even a bad diaphragm can work under those conditions. That's why I like pumping the primer ball while it is running because you effectively take over for the pump.

 

[oldboat1]

Replace the diaphragm. Regardless of configuration, if a diaphragm has lost its flexibility (feels hard, takes on a set, etc.) it won't do the job.

 

[toddschubert]

Thank you all for the responses.
Sorry I called the primer a pump. I know it's just a valve. I guess the act of pushing the key gives one the feeling of activating a pump. I closed it off temporarily but I never hardly had to use it anyway. My motor cranks right up almost every time. However it will get replaced (btw not good for engine but a closely measured spray of carb cleaner cranks her right up if it has been drained of all fuel and needs help lol ((I did have one run away once hence "closely measured"))
Anyway. I'm going tomorrow to get fuel pump parts. I hope that works. It really does seem as if the fuel pump works but does not keep up at higher rpm. Like I said it will idle all day.
FED. I am always learning but the operation of the solenoid and red lever came a long time ago. The solenoid shorted out and melted the plastic valve allowing constant flow of fuel to carbs. I didn't figure this out till late in my troubleshooting when I happened to pump bulb with all plates removed and saw fuel gushing out of both carbs. I had just rebuilt carbs so I knew it wasn't coming from bowl float valves.
Thanks again yall. I'll post results of fuel pump rebuild hopefully tomorrow.

 

[Fed]

Anyone reading this thread should first read the previous thread, here's the link.
http://forums.iboats.com/forum/engi...0spl-rough-and-lots-of-thick-oil-from-exhaust

How did you 'seal the primer' out of the system todd?

I now have an issue where the engine runs after pumping bulb but shuts down after a few seconds. It will Idle all day and run high speed for a few seconds after idling.

The symptoms you describe seem to contradict each other?

 

[toddschubert]

Sorry for the confusion there fed. I should have elaborated on "runs". It idles but won't "run" at high speed. Bad choice of words... Very confusing, I agree. I write like I think and unfortunately it takes a little reading between the lines to fully comprehend.

I disconnected and plugged the fuel line going to the primer with a bolt and hose clamp and used reverse of same to plug the input nipple on primer housing. Then I hooked the purple electrical feed to the inside of carburetor bowl. ( just kidding, it's taped up but that would make for some good fireworks on new year's!). I plan to replace the primer Assy. After holidays ($200+)

THE GOOD NEWS!!!!!
I traveled 2 hrs to get fuel pump parts and then got right to work rebuilding the it. Wham! She cranked right up and since I don't have a big enough barrel I took her to beautiful lake Ponchartrain down the street from my house and she flew like the wind and kept on going!
I was so happy I texted my friend who owns a lakeside restaurant and said " look out the window b**ch! As I performed large high speed fig. 8s.
I feel like a kid with a shiny new bike and a StarWars light saber. Got home and went to work putting all the left-over bolts in place and cleaning her up. When she was running rich, oil was spewing from exhaust as mentioned in prior post and all that crap got tracked into the white textured gel coat floor of the boat and I'm having some trouble getting it all off. Going fishing near the Rigolets in the morning where the trout are tasty and the reds are fightin'
Have a safety concern with "safety steering" (manual) allowing the boat to occasionally make sharp right turns on its own. I haven't looked at what might be allowing this yet but I will start a new thread on it.

Thanks to all esp. Jakedawg for cutting right to the chase.

Merry Christmas to all and to all........