Fuel pump Diaphragm and check valves How to??

I am looking for a how to on this, I know it is probably in the manual, but I prefer how to's as people can give their experience and certain things to look out for. I really appreciate any help. I think we should make a sticky and compile all the how-to's (Force specific etc.) so it will be much easier to find info. If I have time I will start one.


my issue I am having is kiling at idle due to what i am assuming fuel delivery issue

Re: Fuel pump Diaphragm and check valves How to??

Make sure the gasket is towards the engine side and the diaphragm is towards the fuel pump. The check valves are not too bad to replace. The first 2 are a snap but the third is tough. My solution was to get a paint can opener or similar hooked tool and clamp it in a vise, you could try 2 openers back to back. Then I took an insulated pair of pliers and laid it over the fuel pump. I placed the fuel pump/check valve onto the business end of the paint can opener and hit the insulated pliers with a hammer-lightly but firmly. About 3 taps and it was clear.
Now about your issue, it definitely could be a fuel pump issue but it may not be. What are your rpms at idle? Is your timing set properly?

Re: Fuel pump Diaphragm and check valves How to??

We are good but until we know what's going on it's hard to make a diagnosis.
LOTS!!!! more info.Fill out the profile.No sectrets here.J

Re: Fuel pump Diaphragm and check valves How to??

Sorry, I just figured I would start with the diaphragm and check valves as they seemed to be an easy thing to do. The boat I am working on is a 1990 bayliner Capri 16' 90hp hell drive.

Short story of it:
Bought it with ignition issues, fixed those replaced stator cdi box (icm or whatever you call it) and coil packs. Had trouble timing it so brought it in and had it done. Ran good until the idle dropped to around 600 then would die while shifting etc. Let it sit over winter and started working on it again the other day. Tried just adjusting the carbs and got it to run good on muffs. Through it in the water, back down to low idle, and would only reach 2400 rpms. Took the carbs out cleaned all the jets etc reset the idle air screws back to 1.5 turns out (now know that might be a little too far, so am going to redo that) put it back togethor and runs pretty well. Took it to the river, and at first had low idle then after opening it up it started to idle good. Well after about an hour of cruising and just about to put it back on the trailer low idle again. Around 5-600. And on too of that reverse is inop now, but think it's just a cable or linkage issue.

Sorry if this is hard to understand I am just on my iPhone right now, so excuse my punctuation.

Re: Fuel pump Diaphragm and check valves How to??

Ok to sum up my last hard to read message.

1990 bayliner capri 90 hp L-drive
Idle is 500 rpm or so
Timing should still be good, but possibly off as it may have a slight misfire at idle
Dies when put into gear, unless you rev it in neutral a bit and quickly put into gear.

And on a side note reverse is not working, but pretty sure I know the issue.