Hey everybody, looking for some opinions on replacing my fuel pump.

First, some background. I got my 85 GS a few months ago after it had been sitting for 4-5 years and have slowly been getting it back to running condition. Rebuilt carb (reused needles and seats), floats adjusted exactly to factory spec and needles move up and down freely, fuel lines and filter replaced, fuel drained and refilled with 1oz per gallon premix (OMP had been removed by PO). I also added another fuel filter in the engine bay.

I’ve managed to get the carb running pretty well, it’s got a bit of a choppy idle at 900ish rpm but revs and pulls strong. I took it out for a shakedown drive today and made it right at 20 miles before it sputtered out and died. Ran great up to that point at all rpm and throttle ranges. After sitting 2-3 minutes I got the car started up again and drove it the last mile or so back to my dads shop where it’s lived while I’m working on it.

While I was stopped I popped the hood and noticed the front float bowl was showing 1/4-1/3 full. It was acting like it ran out of fuel but I had just filled the tank at the beginning of this trip.

Got back to the shop and checked the fuel pump flow and it only pumped about 500cc in 60 seconds so I’m leaning towards replacing the fuel pump. I’ve been doing some searches and reading old posts and didn’t really see anything similar to what happened to me, most problems I saw here were either rpm capped or went way shorter distances before running out of fuel. I haven’t gone through the tank vent system yet so that’s an option too.

Any ideas on things to look at before I put a pump in this thing? I already know the OEM pump is NLA so any recommended pumps or any to stay away from?

 

Try replacing the fuel filter and try the flow test again.

 

Check yer fuel filter, I bet its clogged up. Either that or theres crud in the tank that gets in the way when fuel is being sucked up. Less likely it could be an ignition issue like a blown coil or ignitor going out.

 

an 85 also had an in tank filter. there is also a relay, so you might check the voltage at the pump too

i've done some testing and i like the factory pump. it works really well. pressure is steady and it moves plenty of fuel.

the early pump is available still, 8871-13-400B

 

The main fuel filter was replaced right before that drive and looked clean when I got back so I'm going to have to drop the tank and check inside. I hadn't gotten to replacing the crusty fuel hoses coming directly off the tank yet anyway so they may be pulling air or the in-tank pickup may be plugged.

Thanks for the replies!