What does this line do?

**whipper** · 05-28-2008, 01:04 AM

I found this looks to be vacuum line off circled in red. What is its function? My motor stops pulling at 6100 its a 225PM with 7500 limiter. This is not my motor Simmons I think just for

illustration. Could this be the culprit?

**whipper** · 05-28-2008, 01:34 AM

Its a pressure regulator. The line off the top does what?

**stiletto200** · 05-28-2008, 05:12 AM

being fuel injected i'd say it is for the fuel pressure regulator.as you gas it up it'l suck more thus upping the fuel pressure

**pyro** · 05-28-2008, 06:15 AM

Originally Posted by stiletto200

being fuel injected i'd say it is for the fuel pressure regulator.as you gas it up it'l suck more thus upping the fuel pressure

I thought that fuel pressure remains constant.

On my motor, that fitting on the regulator tees into the TPI vac hose. When I installed my PCU (doesn't use a TPI), I clipped out the tee and just hooked the regulator barb directly to the hose barb on the intake manifold.

**shawnjetton** · 05-28-2008, 06:26 AM

i cant see the pic but i agree with pyro. thats how mine is set up. the ecu fuel map gets sucked on by the little hose the pulles differant amounts of vaccum called load at differant rpms which sends the amount of fuel by the injector according to a certain percent which has been programed for that load and rpm. if the hose is unplugged it will run full rich

**pyro** · 05-28-2008, 06:45 AM

Ah OK, maybe that's what the Aussie fellow was trying to say. Manifold vacuum DOES control fuel delivery in this sense by measn of the MAP or TPI sensor, but not by means of the vent hookup on top of the regulator.

**whipper** · 05-28-2008, 10:32 AM

OK, rich idle and rich mid range how does it affect fuel dilivery at wot? Would I still get full fuel delivery? The reason I ask is at WOT im only getting 6100. Im pretty sure its a timming issue because I set the timming myself and now I think I didnt do it right.

This line off would explain a flooding feel after idleing and shut down. Was hard to restart. At wot though she stops pulling at 6100 and starts to lurch.My feeling is im retarted on the timming thus not getting full power. im going to see a guy today about getting my timming checked and pick up a new line.

**TheRickster** · 05-28-2008, 11:46 AM

The line hooked to the top of the regulator is a vaccum reference port. Under idle and steady cruise conditions , when the engine is pulling it's greatest vacuum, it will drop the fuel pressure by about 5-7psi. When the engine is under it's heaviest load the vacuum will be the lowest thus the pressure will go to the default setting of 39-42psi. IF you disconnect the line to the regulator it will fatten up the engine slightly in the high vacuum/low load areas...

Rick

**pyro** · 05-28-2008, 12:27 PM

Wow, that's news to me. Interesting.

I always thought that pressure was kept constant, and the ECU's fuel curve and resulting injector duration was used to precisely control fuel delivery. hmmph. We learn something new every day...

**Reaction19** · 05-28-2008, 05:48 PM

I see this motor in the picture has no bleed lines whats up with that what does that do and also can it be done to a 250efi.

**Reaction19** · 05-29-2008, 10:15 AM

anybody!!!!!

**Markus** · 05-29-2008, 10:38 AM

Originally Posted by pyro

Wow, that's news to me. Interesting.

I always thought that pressure was kept constant, and the ECU's fuel curve and resulting injector duration was used to precisely control fuel delivery. hmmph. We learn something new every day...

Injector pulses cannot be made short enough for a decent idle. Therefore, the pressure regulator varies the pressure as well.

**pyro** · 05-29-2008, 11:53 AM

Ahhh... I eat crow then. I was wrong. Sorry for doubting fact, and thanks for filling me in.

**Casey** · 05-29-2008, 12:42 PM

Originally Posted by pyro

Wow, that's news to me. Interesting. We learn something new every day...Ahhh... I eat crow then. I was wrong

wow, did i read that correctly? you mean you didn't know that already?

sorry dude i just had to

**whipper** · 06-21-2008, 03:03 AM

Thanks guys everything is Good now! Just gota set up my timming again. I got Jays TDC guadge and the 0 mark on the ProMax was off by two deg. Im running 22 or 23 i figure right now. No harm retarted but its killing my top end a bit. Ill set her up to 25 at 3000 rpm and see how she likes that. In the manual for the 96 225ProMax the timming is a little unclear? One page says 23 deg and the other 25 at 3000rpm? What would the differance be in timming if set to 25 at 3000rpm and the crank speed timming after set at 3000? Would the crank speed timming be higher or lower than 25 or the same?

Should I just set at 25 turning it over?

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