intake moan

[73stallion]

hey all, when my '99 4.0 OHV sits and idles for a bit i get a moan in the intake, but not all the time. i unplugged the IAC the other day when it was doing it and it shut up. when i plugged it back in right away it didn't do it any more. i was also told by the PO that it needs a fuel pressure regulator because it's hard to start. any thoughts?

as far as the hard start, it fires up pretty easily first thing in the morning. otherwise i have to crank it 3, 4, sometimes 5 times to get it to fire.

 

[NHale623]

I think you should clean your Idle Air Control Valve.

I think you should test your fuel pressure.

 

[zukman]

check out this thread it may help woooooooooooooooooooo lol
http://www.explorerforum.com/forums/showthread.php?t=191913&highlight=IAC+valve

 

[73stallion]

wow, that's funny! i'm gonna take that little piggy apart and see if i can't clean it. if not i may just put my own little filter of some sort on there in it's place, maybe off to the side of the engine bay via vacuum line.

 

[73stallion]

well i took that little black cap off, took it apart, and blew out the 2 filters. i haven't heard another sound out of it. i guess they get dirty and it can't breathe when it needs to.

the hard starts still continue though.

 

[73stallion]

well it's definitely pressure regulator. i borrowed a friends pressure tester this morning. when i turned on the key it slowly went up to about 35 lbs then dropped immediately.

 

[allbobbersrule]

I have a 99 model with v6, I have an intake moan, but only after it is driven for a while, new mass airflow sensor, new tps, new iac, moaning started after those were replaced, still need to do plugs wires and coil, but no starting issues at all, no check engine, sooooo what could it be? the moan will go away when engine is reved a little, sometimes it comes right back thos, car dies once in a blue moon, mainly when turning a corner with no throtle, or when comming to a stop, very rare now, but also it seems like it looses fuel & will idle bad till a little throtle is given, this is while sitting at a stop sign or stop light.

 

[koda2000]

The noise very likely your IAC valve. You can try cleaning it, but that's never worked for me. If cleaning it doesn't work you will need to buy a new one. They just wear out at some point.

 

[allbobbersrule]

The noise very likely your IAC valve. You can try cleaning it, but that's never worked for me. If cleaning it doesn't work you will need to buy a new one. They just wear out at some point.

It has a new IAC, also a NEW Mass airflow & a new TPS, starts great, when cold idle is a little high, but comes down in a couple of moments usually, moan does not start till it has been driven for a bit, per what i am reading, it is the fuel pressure damper (regulator), so i will get it next & a new fuel filter

 

[koda2000]

It has a new IAC, also a NEW Mass airflow & a new TPS, starts great, when cold idle is a little high, but comes down in a couple of moments usually, moan does not start till it has been driven for a bit, per what i am reading, it is the fuel pressure damper (regulator), so i will get it next & a new fuel filter

I believe some '99's still had a rail mounted fuel pressure regulator and some (the ones with the return-less style fuel systems) had the tank mounted FPR. Which do you have? You should be able to isolate the noise more easily using a mechanic's stethoscope or a long screw driver with the handle held against your ear. Also listen to your PCV valve. If it ldles rough at first and then smooths out it might need intake manifold gaskets.

 

[J_C]

If the regulator is in the tank, you probably ought to replace the pump while you're at it. However you should measure your fuel pressure first. If the pressure is fine, I doubt you have much to gain from replacing the regulator.

 

[koda2000]

If the regulator is in the tank, you probably ought to replace the pump while you're at it. However you should measure your fuel pressure first. If the pressure is fine, I doubt you have much to gain from replacing the regulator.

I don't know that you can even purchase the in-tank fuel pressure regulator separately. I've never seen one offered by anyone. New ones are part of the complete fuel pump assembly. Besides, I don't think it's the kind of thing what would "moan" if it was bad. IAC's most definitely moan and make woooo noise when they go bad. PCV valves have also been known to make noises and they typically make their noises at warm idle. I've replaced 2-3 of them over the years.

 

[allbobbersrule]

I don't know that you can even purchase the in-tank fuel pressure regulator separately. I've never seen one offered by anyone. New ones are part of the complete fuel pump assembly. Besides, I don't think it's the kind of thing what would "moan" if it was bad. IAC's most definitely moan and make woooo noise when they go bad. PCV valves have also been known to make noises and they typically make their noises at warm idle. I've replaced 2-3 of them over the years.

Mine is an OHV 4.0 & the damper (regulator) is on the engine not in the tank, this i do know

not the PCV valve, it idles smooth till the regulator starts doing the wrong thing & then it dies or runs like it is about to die, rpms drop as well

 

[J_C]

I don't know that you can even purchase the in-tank fuel pressure regulator separately. I've never seen one offered by anyone. New ones are part of the complete fuel pump assembly. Besides, I don't think it's the kind of thing what would "moan" if it was bad. IAC's most definitely moan and make woooo noise when they go bad. PCV valves have also been known to make noises and they typically make their noises at warm idle. I've replaced 2-3 of them over the years.

I meant that it should be part of the sending unit, yes? There's that, and then the pump if not included with the sending unit. IIRC they can be bought both ways, with pump or without. Here's what Rock Auto shows as a sending unit alone for the OHV 4L... though I can't imagine why anyone would buy it separate given how much money they want for it.

More Information for SPECTRA PREMIUM FG132B

www.rockauto.com

 

[J_C]

Mine is an OHV 4.0 & the damper (regulator) is on the engine not in the tank, this i do know

not the PCV valve, it idles smooth till the regulator starts doing the wrong thing & then it dies or runs like it is about to die, rpms drop as well

If you have a returnless fuel system, you have a damper on the fuel rail but still a pressure regulator on the sender in the fuel tank.

I am not sure how much of an impact a bad damper makes, but it just smooths out the pressure as the injectors activate. I don't think it going bad would make enough difference to notice what you're describing, so I would sooner suspect it is the pump itself or the pressure regulator in the tank that's bad.

If you instead have a return fuel system, then you do not have a regulator in the tank and the one on the fuel rail is a true regulator. If that is the case, you're lucky to have the OHV 4L because the one for the SOHC has been rare, difficult to find for years.