Prostar fuel pump

ScottScott

2017 Prostar, already replaced fuel pump under warranty at about 480 hours, as the check valve wasn't maintaining pressure while sitting resulting in slow starts. Now a little over 800 hours it isn't holding pressure again (no longer under warranty so we'll have to put up the full cost of a new pump.) Has anyone tried to clean the check valve? Or can that item be replaced without replacing the complete fuel pump? Or, has anyone tried putting in an inline check valve?

Cnewbert

@ScottScott this isn’t an answer to your question, nor a solution to the problem. But I’m told a quick fix to the slow start/long cranking issue due to sitting around too long resulting in a loss of fuel line pressure is to turn the key off, then on again. This re-pressurizes the fuel line. Of course then it has to go through the boot-up sequence which takes a little time itself. Again, this is not a substitute for a functioning check valve. I’m intrigued by your idea of an in-line check valve and look forward to any additional discussion of that.

ScottScott

Yes, the pressure regulator SHOULD maintain pressure while sitting. Turning on after having it off (key off) should run the fuel pump to re-pressurize the system. Even doing that its taking a while to re-pressurize. LOONNNGGG cranking. Last time, after a couple key off/key on it finally started right up. Once started, it runs perfect (hard acceleration and full throttle.) I'm trying to see if I can source the pressure regulator (probably a @ $50 part.) If not I'll try the inline check valve (also @ $50 part.) Either way its much better than $800 or so for a full fuel pump replacement.

Mastercrafter

Unless air is entering the fuel system with the pump off, re-pressurizing should be almost instant. It’s not like it’s filling up a tank— just a 3/8 fuel line. The time it takes from key-on to start button should take care of it.

How old is your battery? What’s voltage say when cranking? Mine was dropping to 8v and cranking slow, and that also means weak spark. New battery, much better.

Plugs, wires, distributor cap age?

ScottScott

@Mastercrafter

Good thought....Battery could be questionable, and was a consideration. I can't remember how low it was dropping during cranking. Do you know what would be normal? But during the slow start and key on/off a couple times......when it did finally fire after a key on, it fired right up.

Testing fuel pressure now. As you stated, from 0-60 it was fast for 1st time turning on. Then it dropped fairly rapidly to 40-45 then continued dropping slower till it stabilized at 30. That's probably enough to cause a slow start. As it needs so many rotations before is turns fuel pump back on. Turning switch back on it only went to about 55 then dropped quickly again to 45, then slowly on back down to 30.

55 should be enough i believe for a normal start. Not sure what it needs as a minimum.

No doubt it's not holding pressure causing slow starts, and after a couple cranks an aging battery could be causing the extended slow starts.

A couple more key off/on. When key on pump runs holding pressure at 55-57 as long as pump runs. When pump shuts off it drops right away to less than 50 and continues down.

Cnewbert

@ScottScott curious what fuel pressure gauge you are using. There’s lots of fairly inexpensive ones available and I think I’ll pick one up. Personal recommendations are always helpful.

ScottScott

@Cnewbert On team talk, some said they picked up the $15 one from Harbor Freight, then some recommended against it. I was looking into the $40-50 units at various parts stores, then saw another one in the same price range from Harbor Freight that seemed to have better reviews than most at the parts stores, and was in stock close to home Maddox Basic Fuel Injection Service Kit. I cant speak to the quality difference between the actual gauge on this vs others, a big part of the cost is the various adapters included and case it comes in. For the prostar, no adapters were needed.

Jody_Seal

I picked up a harbor freight pressure unit. I be honest it is as good as my 25 year old snap-on
unit and had better fittings and assortment .
it was near $40 though.
the old snap-on was close to $200 back in the day.

VONMAN

@Mastercrafter Good battery and voltage is very important when it comes to fuel injection engines. No only for cranking over, but also energizing the fuel pump's and ignition system and electronics. On my old 200hp outboard I could pull/rope start it by hand if the battery was dead. On the new 200hp EFI with 2 fuel pumps it's no way. And with the Florida heat, I always have a battery tender on it when not using it.

Cnewbert

@ScottScott thanks for the info. I ended up ordering one from Amazon. The kit has way more adapters than I’ll ever need, since all I need is the standard Schrader valve, but it was only $28. Quality appears quite good at least.