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.

[wski1831]

Scott Scott did you find a check valve? Is the boat fixed?

[ScottScott]

@wski1831 The boat is usable, but not fixed. Starts are slow at times. I have seen a number of check valves that look like they'll do the job. I'm still trying to see if I can source the exact pressure regulator so I can just replace and have everything as designed 1st....but that is proving to be difficult.

[ScottScott]

VERY IMPORTANT TO ANYONE CONISIDERING A CHECK VALVE TO RESOLVE THIS ISSUE!!!!!!

 

Upon further research it appears that adding a check valve to a return-less fuel system is a BAD IDEA. The pressure regulator that is part of the fuel pump module used is designed to bleed off excess pressure while also maintaining just enough pressure in the line while not running for a quick start. A check valve will serve to hold the pressure while not running, but will not allow anywhere for excess pressure to go if the heat from the engine heats the gas and causes pressure to increase in the fuel line and fuel rails. This can potentially overload the pressure capabilities of the rails, hose, and injectors potentially causing damage to the injectors or gas leaks that can result in fire. That idea is officially scrapped, and back to trying to source a suitable replacement pressure regulator.

[wski1831]

Thanks for the feedback!! I have a 17 MasterCraft may be in the same boat.

[Cnewbert]

@ScottScott great research on this issue. Thanks!

[Jody_Seal]

@ScottScott Option.

Replace all factory fuel delivery system {top of tank to fuel rail} with a PCM FCC set up.

 

[ScottScott]

@Jody_Seal I see under some PCM specs a fuel pressure of 57-62 which is comparable to the MCs at the rail. But, the PCM rail is 580-2100. Is there a pump on the fuel rail that takes it up to the 580-2100 and the FCC would still work, or does that pressure come off the FCC. Or maybe thats the newer engines?

[skihacker]

That would have to be a direct injection system, second high pressure pump at motor, under intake manifold cam driven.