PDA

View Full Version : Flux Capacitor is not working


Skipper
08-08-2011, 01:23 AM
Needed a catchy title to get somebody to notice and help me out...the boat runs fine for about five minutes, then when I accellerate to pull a skier or simply try to drive 34 mph the boat bogs down. Is it the throttle position sensor? MAP sensor (what is a MAP sensor anyhow).

1995 Prostar 190
Indmar TBI
Hurth 1:1 Trans
Temp: Consistently 160 degrees
Voltage: Varies between 11 and 13
Oil pressure: Usually runs at 40 psi but sometimes shoots up to 60 to 80 psi recently

History: Upgraded to Stargazer Friday. The boat ran just fine Friday and Saturday. Saturday afternoon I went to the local gas station to fill two five gallon cans. Put the gas in the boat but the wind kept me from skiing Saturday evening. Sunday morning, boat started just fine. Drove about 1/2 mile to the slalom course - just fine. But the boat would not run more than 30 mph.

Trouble-shooting: Went to the Perfect Pass first. Checked the throttle cable, servo, and settings. Everything checked out - just fine. With the Perfect Pass turned off the boat still only revs out to about 3000rpm.

Repair: I pulled the fuel cell. Dumped all of the fuel. Removed the fuel lines. Blew out all of the fuel lines. Put it all back together. Filled up with 10 gallons of premium fuel.

The result: NOT FINE! After launching the boat accellerated normally. Ran at various speeds between 24 - 38 mph. Stopped and accellerated to 34 mph with Perfect Pass engaged. Ran just fine. But after a few minutes it began to bog down.

Somebody help me, please.

Skipper
08-08-2011, 01:35 AM
Another question...is there supposed to be a fuel filter at the top of the fuel cell on the line that leads to the fuel pump? There is not one on my boat. The line has been cut and hose clamped to a barbed fitting. Definately not stock.

Second question. If there is supposed to be fuel filter...can I just install one with hose clamps?

What the heck is wrong with my stinking boat?

robin
08-08-2011, 04:49 AM
I believe flux capacitors operate on plutonium. Im not an expert, but you may need a nuclear engineer to assist....probably not a DIY.....

robin
08-08-2011, 04:53 AM
As to fuel filters, my has one right on top of the fuel cell and a 2nd 1 just behind the throttle body. Mine is a 99 tbi 350 indmar.

bret
08-08-2011, 07:35 AM
If you have an external fuel pump, there is a screen just inside the bottom fitting. I have a 94 PS, this was my issue. I found about the size of a Q tip, paper wadding I guess from the fuel filter, mine is behind the fuel pump, above the trans. Methanol eats at the paper inside.

Not sure about yours but that was my problem.

Skipper
08-08-2011, 11:47 AM
That solves the problem with the flux capacitor. Maybe even the fuel filter. Now does anybody know how why the engine bogs down under pressure?

bret
08-08-2011, 12:21 PM
Do you have an external fuel pump? Did you check the bottom fitting on the fuel pump? If yes disregard but my boat would run fine for 10 minutes, then stumble it's A$$ off, could not get it above 32, then 30, finally it would not run above 28mph. I even got a new fuel pump but it was the wadding up in the fuel pump inner screen.

Skipper
08-08-2011, 06:24 PM
Yes, thank you, I removed the external fuel pump when I blew out all of the fuel lines. I inspected all three ports and they were clear. However, I am going to throw parts at it...a new TPS and MAP sensor. I will install an inline fuel filter above the fuel cell...or should I say reinstall. And when I do all of that, I will reinspect that lower fitting on the fuel pump.

wtrskr
08-09-2011, 11:44 PM
My understanding is that the Map sensor measures vacuum and sends that signal to the ECM so it can use the information to send the correct amount of fuel. A hose goes from the throttle body (at least on mine) to the Map.

Before you go throwing parts at it:

1. I don't think the Map sensors themselves go bad very often.
2. You can check for "codes" to see if your ECM is finding problems with any of the sensors.
3. If it is the Map, I have a brand new Map sensor that I could sell you for a discount (mail it) because I thought my map sensor may have been going bad (was getting an error code).

Do a search for finding codes if you haven't tried that already. You insert a paper clip into the ECM connector and it flashes the codes. It will flash 12 three times (flash, pause, flash flash) then will flash the error code(s) three times. Map sensor should be code 33 or 34 I beleive.

I'm no expert, but just from reading this board I imagine others would suggest you at least test the fuel pressure before throwing parts at it.

JimN
08-10-2011, 12:44 AM
Another question...is there supposed to be a fuel filter at the top of the fuel cell on the line that leads to the fuel pump? There is not one on my boat. The line has been cut and hose clamped to a barbed fitting. Definately not stock.

Second question. If there is supposed to be fuel filter...can I just install one with hose clamps?

What the heck is wrong with my stinking boat?


Pull the hose from the barb (which was stock on many boats)- I bet you'll see a spring if you look in the hole on the end with the barb and a metal ball at the other end. Make sure the spring and ball aren't rusty. If they are, you'll want to remove this fitting and clean it, or replace it. This is the anti-siphon valve and if it can't move freely, it will restrict the fuel flow.

Not all boats had two filters- don't worry if you replace yours frequently.

JimN
08-10-2011, 12:47 AM
That solves the problem with the flux capacitor. Maybe even the fuel filter. Now does anybody know how why the engine bogs down under pressure?

As I posted in the other thread, check the fuel pickup tube. If it's clogged, it won't necessarily act up immediately. At idle, the flow rate isn't very high and once you goose the throttle, any blockage makes more of a difference.

Did you check the vent, yet?

Skipper
08-10-2011, 11:38 AM
As I posted in the other thread, check the fuel pickup tube. If it's clogged, it won't necessarily act up immediately. At idle, the flow rate isn't very high and once you goose the throttle, any blockage makes more of a difference.

Did you check the vent, yet?

I disassembled the fuel cell and drained all of the fuel. I disconnected, drained, and blew through all of the fuel lines. I cleaned the metal screen on the fuel pickup tube. I did not blow out the vent tube. I added that to my list.

Would a clogged vent cause the engine to bog down like that?

JimN
08-10-2011, 12:23 PM
I disassembled the fuel cell and drained all of the fuel. I disconnected, drained, and blew through all of the fuel lines. I cleaned the metal screen on the fuel pickup tube. I did not blow out the vent tube. I added that to my list.

Would a clogged vent cause the engine to bog down like that?

It can, and does cause it. The reason they went to the in-tank pump is because it's far easier to maintain high pressure when you push the fuel, as opposed to pulling it from the tank. If the vent is clogged and the tank isn't pressurized (like a car or truck), using gas creates negative pressure in the tank and that's about as close to crimping the fuel line as you can get without actually crimping the fuel line.

When you blew the lines out, did you to it from back to front, or front to back? If you did it from front to back, it won't show problems, like fuel line delamination. Do you have an outboard motor gas tank that you can use as an alternative fuel source? Make sure it can't move and be sure to have a fire extinguisher handy, just in case of trouble. If it runs OK, it would seem that the problem is in the fuel pickup area (pickup tube, anti-siphon, shut-off valve).

If you replaced the fuel filter, did you see an arrow on the side? Maybe you got a defective filter- just a thought.

Skipper
08-10-2011, 10:51 PM
I removed the vent line and and the vent. Both were free of any obstructions and allowed air to flow freely. I was really hoping that would be the problem.

I blew the fuel lines out from back to front. I did not observe any deposits or any other indicators that something was in the lines or wrong with the fuel.

I removed the hose to the MAP sensor and did not find any liquid in it.

I will remove the fuel pump, again, and do a more thorough inspection of the inlet screen.

Keep the suggestions coming. I really would prefer to ski than work on the boat.

1redTA
08-10-2011, 11:07 PM
1.21 Gigawatts! you need to put a metal whip leading to the flux capacitor ( lightning strikes ) or install a Mr. Fusion

Skipper
08-10-2011, 11:48 PM
1.21 Gigawatts! you need to put a metal whip leading to the flux capacitor ( lightning strikes ) or install a Mr. Fusion

I tried burning bannana peels. Still bogs down at 3000rpm.