Weekend from hell...Need a fuel pump

[chpthril]

So after a lot of digging and some help from Anhaney, we discovered that MercCruiser recommends that if you replace the fuel pump and cooler, you should replace the fuel regulator too. Thats where I'll start and see if it fixes the problem.

Good luck, let us know.

[TeamAllen]

I just replaced the fuel pump, cooler assembly and anti siphon valve last night. I re-used the regulator. I'll see how it does next week at Shaver Lake.
You might need to replace the two cooling hoses attached to the fuel cooler. The ends, of the rubber hoses, on mine were fused onto the copper tube. Save yourself time, buy new hoses and cut off the old ones. That is a tight place to be working with that plastic housing getting in the way sometimes.

I don't think the anti-siphon valve was it. It looked good and moved just as free as the new one. I replaced it anyway. The new pump sounded strong. The old pump occaisionaly got this high pitched whine. Especially after it would vapor lock.

I thought about this some more today. Would a different octane of fuel make a difference. I know higher octane fuel has a slower burning rate. Would different octane fuel, vaporize any more or less? I have used 91 and 89 octane in the past but after reading some posts have moved down to the 87 octane. Any thoughts.

[jleger98]

I just replaced the fuel pump, cooler assembly and anti siphon valve last night. I re-used the regulator. I'll see how it does next week at Shaver Lake.

One end of the cooling hoses was pretty fused, I was able to cut the end off and reuse it. The other end came off pretty clean. I should have my regulator either tomorrow or Monday, so I'll know if its helped after that. Hopefully you won't have any trouble, but I would consider replacing the regulator, as MC suggests it. Anhaney can get it a lot cheaper than any place I found it. Part # is 807952A 1 if you need it.

[TeamAllen]

The cheapest I found the regulator is $75. I will see how it goes this week. I'm glad you were able to save the hoses.

[jleger98]

Ok, so after the crappy weather finally went away, we had a perfect Labor Day weekend. mid 80's light wind. You think I spent time on the boat?? HEEEELLLLLL no. Had to rebuild the deck. Long story.....Anyway. Monday we finally got out on the boat. This is the first time since adding the fuel regulator, so I was anxious to find out if the problem went away.

Boat ran great for the first 3 hours. We were just about to come in when BAM same issue. We had just got done draining the sacs, (so had been stopped for about 10-15 mins) I started it up, and as soon as I applied throttle it bogged, and only because I jacked the throttle around did I get it to go. I don't get it.

We had it warmed up, running etc, stopped and swam, ran it again, stopped and swam with no issues.

So, new fuel pump, new fuel regulator, new dist cap and rotor, and still the problem persists. Anyone got any ideas? Ignition modules under the dist cap?? Anything else???

[TeamAllen]

Wow! Now you've got me worried again. The only things I did was replace the fuel pump water cooler combination and new anti-siphon valve. I haven't got to the regulator yet. My problem has not returned.

Did you replace the copper cooler part as well as the fuel pump? Or did you replace the fuel pump only?

Did you replace the anti-siphon valve?

[R&T Babich]

That was my question, too. Did you change the anti-siphon valve? Or you could temporarily eliminate it as a suspect by replacing it with a 1/4" NPT x 3/8" hose barb.

It would be interesting to know what the fuel pressure is in the fuel rails (MPI) or at the throttle body when the problem is happening. That would help determine if it's fuel supply related or not.

Was the engine running while you drained the sacs? The battery could have been drained. I can't think of a reason why that would matter, but did you do the same thing when it happened before?

[teachercop]

The fuel pressure I measured during the 'vapor lock' episode at Lake Powell was a fluctuating 3-9 psi at approximately 4300 feet elevation. Measurement taken from the Fuel Rail.

Did you shoot cold water on the fuel pump when it was having its episode?

[TeamAllen]

I posted these other links about this in another thread. I'll link you to my quote. I think it's worth reading at least.

http://www.tigeowners.com/forum/show...9&postcount=31

[jleger98]

Did you replace the copper cooler part as well as the fuel pump? Or did you replace the fuel pump only?

Yep.

Did you replace the anti-siphon valve?

Nope, but I can't see how that could be the issue. Every time I've taken it off it moves freely.

It would be interesting to know what the fuel pressure is in the fuel rails (MPI) or at the throttle body when the problem is happening. That would help determine if it's fuel supply related or not.

Yeah, having a hard time spending the 100 bux for the tester, only to use it once

Was the engine running while you drained the sacs? The battery could have been drained. I can't think of a reason why that would matter, but did you do the same thing when it happened before?

Engine was not running, but the blower was on the whole time.

The fuel pressure I measured during the 'vapor lock' episode at Lake Powell was a fluctuating 3-9 psi at approximately 4300 feet elevation. Measurement taken from the Fuel Rail.

Did you shoot cold water on the fuel pump when it was having its episode?

No, the whole episode only lasted about 5-10 secs before I was able to get it to go.

I posted these other links about this in another thread. I'll link you to my quote. I think it's worth reading at least.

http://www.tigeowners.com/forum/show...9&postcount=31

Thanks TA. I'll take a look-see.

[jleger98]

I posted these other links about this in another thread. I'll link you to my quote. I think it's worth reading at least.

http://www.tigeowners.com/forum/show...9&postcount=31

My old Supra had a vent on the motor cover. Do you guys think that would make a difference? I see some suggestions on these links that say just open the motor cover for 5 mins....etc. Pretty tough to do when you have sacs all around it.

[dogbert]

I have what may be a silly question. Do you have something obstructing your fuel tank vent (either a kink in the line or perhaps some insect made a nest in there)? An easy way to find out would be to open your gas cap and if there's a rush of air going in the next time you experience this, then this might be your problem.

[jleger98]

Well, interesting thought. The vent is on the same side we surf on. I wonder if that has something to do with it. That said, when removing the anti-siphon valve in the past, there was no release in pressure that I noticed. Is that vent a one-way deal or is it just an open line to the tank?

[dogbert]

Where is your vent? Mine's in just below the front windshield. If yours is further back, it might be getting submerged (not good). The vent is an open line. I've had fuel spill out of mine when I overfilled it. I'm not sure what happens when liquid flows in from the outside.

[jleger98]

Mine is port side, right about even with the peak of the windshield. Anyone else run into this? Maybe I should go out and *GASP* not fill the bags for the day and see if it still happens......that would suck.....relatively speaking. Still a day on the water without sacs is better than a day in the office.