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  #11  
Old 03-12-2016, 04:20 AM
Thaiwake Thaiwake is offline
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Can anyone explain how the fuel pressure regulator actually works? There is a regulator on the injector rail and then the round one on the top of the tank. I can blow both ways through the regulator on the tank so I guess there is no valve in there. Why are there 2 different types of fuel pressure regulator in this system??
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  #12  
Old 03-12-2016, 08:07 AM
chrislandy chrislandy is offline
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In crude terms a pressure regulator is a valve or diaphragm with a spring on it, the fuel pushes on the valve and when it gets to the point where the pressure is greater than the spring it opens slightly to prevent more pressure build up, if the pressure drops then the valve closes maintaining the desired pressure. The excess fuel let through the valve then returns to the tank.

If there is no regulator, the pressure will build up to whatever the pump can produce, if there is no regulator and a fuel return then no pressure with be aquired.

Some early EFI systems (probably not on boats though) just used a pin hole as a regulator and a pump that could only achieve just over the required pressure.

I'm not sure what the second thing is on the tank
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  #13  
Old 03-12-2016, 09:56 AM
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JimN JimN is offline
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Originally Posted by Thaiwake View Post
haha, thankfully no croc's but the jellyfish can help to keep you up on the board that's for sure

Got another question if you guys can help:

I just went down to review some of the other work the mechanic has done and there was another thing that didn't sit right with me. Next to the battery isolator switch there is a small square black box that I think is the voltage regulator. There are 2 red wires on either side that go to the battery switch and a black wire that comes from the middle pin on the box. This black wire was detached from the engine and I didn't know where it came from. The mechanic told me I don't need it and to leave it detached. Now I am starting to question his wisdom, to be fair the engine was running ok without it but I would like to know where it is supposed to attach to??

I think it might come from the alternator but not 100% sure and also not sure if it goes to the positive or negative terminal. Can you guys enlighten me?
Can you post a photo? The voltage regulator should be inside the alternator.
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  #14  
Old 03-12-2016, 09:59 AM
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CantRepeat CantRepeat is offline
 
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Does the black box look somthing like this?

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  #15  
Old 03-20-2016, 09:41 AM
Thaiwake Thaiwake is offline
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So just got my in tank fuel pump and still having similar problems to the other pump. I am thinking now I might have damaged the fuel pressure regulator by putting too much fuel in with the out of the tank pump. I checked fuel pressure and it was ok at idle but when I put the throttle down the pressure went above 70psi.

Is it possible that I damaged the fuel pressure regulator?

Is it easy to change the regulator on the injector rail? It looks like it's welded in so not sure if I can just pull it out?

Do you think there is any chance I damaged the circular regulator on the top of the tank or is it more likely the regulator on the injector rail?

Not sure what to do next? I don't think it is a problem with the pump. Can anyone suggest the next move after the fuel pressure test showed too much pressure?

The engine seems to run fine at idle, then if I pump the gas in neutral it will accelerate to 5700Rrpm and all sounds good. When I try and run in gear it runs fine up to 2500rpm then won't go much further than that. Sometimes it will go up to 3000, but then surges,loses power or dies.

I have sacked my mechanic but how do I repair the damage he has done?

Thanks for any help

Last edited by Thaiwake; 03-20-2016 at 10:00 AM.
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  #16  
Old 03-20-2016, 10:14 AM
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CantRepeat CantRepeat is offline
 
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I'm pretty sure the regulator is onto of the tank.

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  #17  
Old 03-20-2016, 10:23 AM
chrislandy chrislandy is offline
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Check your plugs are firing in the correct order, mine (TBI) did something very similar and some numpty in the past had got the plug leads to 6 & 8 (or 5&7) the wrong way around. - took it for a drive up the lake then stopped, floated and checked each plug, 6 were nice and 2 were wet, swapped them over and all good after that

It seemed to idle OK and would free rev with no issues, but wouldn't go over 3000rpm, kept dying, dropping power etc
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  #18  
Old 03-20-2016, 05:44 PM
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JimN JimN is offline
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Originally Posted by Thaiwake View Post
So just got my in tank fuel pump and still having similar problems to the other pump. I am thinking now I might have damaged the fuel pressure regulator by putting too much fuel in with the out of the tank pump. I checked fuel pressure and it was ok at idle but when I put the throttle down the pressure went above 70psi.

Is it possible that I damaged the fuel pressure regulator?

Is it easy to change the regulator on the injector rail? It looks like it's welded in so not sure if I can just pull it out?

Do you think there is any chance I damaged the circular regulator on the top of the tank or is it more likely the regulator on the injector rail?

Not sure what to do next? I don't think it is a problem with the pump. Can anyone suggest the next move after the fuel pressure test showed too much pressure?

The engine seems to run fine at idle, then if I pump the gas in neutral it will accelerate to 5700Rrpm and all sounds good. When I try and run in gear it runs fine up to 2500rpm then won't go much further than that. Sometimes it will go up to 3000, but then surges,loses power or dies.

I have sacked my mechanic but how do I repair the damage he has done?

Thanks for any help
I don't know your legal system, but if someone damages anything that is owned by someone else, they should be responsible for the repairs to make it right.
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  #19  
Old 03-20-2016, 06:00 PM
KyleNowad KyleNowad is offline
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Quote:
Originally Posted by Thaiwake View Post
So just got my in tank fuel pump and still having similar problems to the other pump. I am thinking now I might have damaged the fuel pressure regulator by putting too much fuel in with the out of the tank pump. I checked fuel pressure and it was ok at idle but when I put the throttle down the pressure went above 70psi.

Is it possible that I damaged the fuel pressure regulator?

Is it easy to change the regulator on the injector rail? It looks like it's welded in so not sure if I can just pull it out?

Do you think there is any chance I damaged the circular regulator on the top of the tank or is it more likely the regulator on the injector rail?

Not sure what to do next? I don't think it is a problem with the pump. Can anyone suggest the next move after the fuel pressure test showed too much pressure?

The engine seems to run fine at idle, then if I pump the gas in neutral it will accelerate to 5700Rrpm and all sounds good. When I try and run in gear it runs fine up to 2500rpm then won't go much further than that. Sometimes it will go up to 3000, but then surges,loses power or dies.

I have sacked my mechanic but how do I repair the damage he has done?

Thanks for any help
Show up at his house demanding he fixes what he messed up.
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  #20  
Old 03-20-2016, 11:05 PM
Thaiwake Thaiwake is offline
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Thanks for the replies guys. Can't repeat, I think this is part of the regulation system, but I thought there was a regulator attached to the fuel rail. The regulator on top of the tank I can blow through both ways, so doesn't seem to have a valve in it. I don't know exactly how this system works so not sure if which part might be the problem.

I'll go down and check the firing order in a bit, pretty sure it's all ok but you never know.

No legal comeback out here unfortunately, this is Thailand and there are very few qualified or insured mechanics and as a foreigner I wouldn't stand a chance of getting anything back. I don't really want him to fix what he's done either as he might make things worse.

Is there anyway I can test the two components to be sure what has broken? The circular regulator on top of the tank and the small regulator on the injector rail? I don't know if I mentioned the engine is a 350MCX.

What could be the reason for too much fuel pressure on acceleration?
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fuel module, fuel pressure, fuel pump

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