92nsx

Keep us up to date if the fuel pump / low pressure was the problem.

Nick616

Shop got the cool fuel pump, cooler, and regulator replaced - found both of the "low pressure" hoses ( supply from the mechanical pump, which is apparently not stock but probably added at some time to help with the cool fuel "issues", and the pressure relief hose ) were collapsed at the pump fittings. They will get those replaced hopefully tomorrow, do a sea test and hopefully problems will be solved. Then I can plan the rebuild for this winter, but at least those systems will be working for sure come next spring. It would have been really unpleasant spending the money on a rebuild only to fight these issues next summer.

SB

iTrader: (1)

A fuel pump doesn't cause too much pressure. A regulator will or an obstruction after.

In fact. a pump doesn't create any pressure, it just pumps against pressure.

Nick616

I think I had some of both - regulator was probably bad and the line that the regulator relieved back to the fuel filter was also probably bad. Two places to create pressure that should not be there.

Will never know the exact culprit - but either way or some of both, it should be solved shortly.

Will have them check timing and codes on the sea trial to see if there is anything else that needs to be fixed. ( I don't have the equipment to connect to the controller. . . )

Nick616

Just talked to my shop - fuel pressure is fixed - now the alternator is not charging . . . will have a new one in the morning.
Fingers crossed all the "gremlins" have been found now!

Nick616

Finally got out for a test run last night. Fuel pressure was holding at 30psi from idle to WOT - seems a little low, but everything is new so I'm not sure why it is not higher or not increasing with higher throttle . . .
Throttle is more responsive and idles better. But no more WOT rpm - still only runs 4000 with drive all the way down, maybe 4200+ with drive trimmed up.
Water temp ( on gauge ) is around 180 when cruising ( 3500 ) went up to 210 on a short WOT run.

I've pretty much accepted that this is all I'm going to get out of her this year, will enjoy what's left of the boating season, and get the engine rebuilt this winter.

Hopefully next year will be better . .

SB

iTrader: (1)

Do not run it with low fuel psi unless you are okay with putting holes in your pistons and lifting the heads.

Edit in: same with the water temp. Don't run it that way !

F-2 Speedy

iTrader: (6)

Agree with SB, those two factors will deff. kill that engine

Sonic30ss

30 psi = lean
Lean= detonation
Detonation = bad boating day

Nick616

Ok - so definately get it fixed . . .

Any thing else to look at for fuel pressure?

My only thought is that the fuel pressure relief line runs back to the fuel filter - if the fuel filter was plugged ( it was new this spring ) or the line from the tank to the fuel filter is clogged / collapsed that there is suction on the relief line that is dropping the pressure to the fuel rail. But I'm no fuel system expert . . .

I'm assuming the correct pressure relief valve was installed . . .

Don't want to have a REAL BAD boating day in the days left this year.

Thanks for the advice so far - I appreciate it.