Primer pump guage

[jimmcld]

I found an old post that talked about the primer guage and if pressure should show when the engine is running, but they never came up with a definative answer. Does anyone know if this guage should show pressure when the engine is running? Should the supply line going to the primming pump have pressure on it when the engine is running?

I believe I'm getting fuel into the intake manifold through the primming pump. I have replaced the o-rings and inspected the check-valves and all appear to be in good shape. However, I have a lot of pressure coming in on the supply side of the pump and it appears to be getting up to the intake.

I haven't been able to find anything in the TM's.

Help,

Jim

 

[doghead]

You do not read pressure when the cold start primer pump is not in use. It only indicates fuel pressure that you make , by hand pumping.

You do not read fuel pressure on that gauge, in normal running condition.

 

[Floridianson]

Yes it will show pressure at full rpm but it will and or should peg the gage only when the primer pump is out.
Try and put a plug in the bottom of the PT where the line comes off it for the primer.

 

[jimmcld]

This is interesting. I have two replies so far and one says it will show pressure and the other one says it will not. I'm still a little confused!!! My guage reads 30 lbs. at idle.

 

[Floridianson]

Yes mine shows 30 at idle with primer in and locked. I said if you leave the primer pump in the out pisition it will peg the gage casue it does not go high enough.

 

[martinsaunders06]

jim, check your pm,s
martin

 

[doghead]

Hmm, my recollection could be wrong. I never really paid much attention to it, after it starts.

I don't think mine reads any pressure. I never leave the handle out either.

 

[Floridianson]

Hmm, my recollection could be wrong. I never really paid much attention to it, after it starts.

I don't think mine reads any pressure. I never leave the handle out either.

Right we would never leave it out but I just tryed it for the heck of it while at full rpm.

I have not taken the manifold valve off yet but I believe there is one more check valve there the does not open till it hit at least 80 lbs or around there. If there was not one there it would not make a spray it would just dribble out the end.

If there is one there and it was leaking that would put fuel in the madifold yes no?

 

[Floridianson]

jim, check your pm,s
martin

If you know something fill us in too please.

 

[crasheej]

Will be no reading unless you are pumping the thing . That is why you buy Tm's when you buy a pice of equipment. Come on people . Get eith the program.

 

[Floridianson]

Will be no reading unless you are pumping the thing . That is why you buy Tm's when you buy a pice of equipment. Come on people . Get eith the program.

You shure about that. What does you gage read when at Idle?
Ane the word is with not eith try spell check.

 

[crasheej]

Cat ealked on the key board what can I say . Mine don't read ahything unless your pumping.

 

[jimmcld]

First of all, I've been all through the TM's and I couldn't find a thing on the subject. It does show you how to replace the guage and the pump.

However, Martin is the man! He knew exactly what the problem was: The supply line to the primer pump was connected to the wrong port on the fuel pump. There are two ports right next to each other, neither of which is marked. The outboard port is pressurized and the inboard one is not. The primer pump should be connected to the non-pressured port.

I have had problems with my truck since I got it about six month ago. It put out a black toxic smoke at idle, would not come back down to idle very fast when reved, and had a run-away twice. I had never noticed the primer guage reading until yesterday. I then starting putting two and two together.

Just went for a test drive after changing the line. Runs better than it ever has, sounds better at idle, and doesn't put out that awful black toxic smoke anymore.

Martin is my hero!

Jim

 

[doghead]

So, with it correctly connected, does it show pressure with the engine running?

 

[jimmcld]

Good question! No, it reads zero pressure all the time now unless you pump on the primer pump.

 

[Floridianson]

Very good then my 816 has the line connected to the wrong port to. Thanks Martin and Jim for what was not in the TM's

 

[crasheej]

Try TM 9-2320-260-20 page fig 2-113,2-114, that is where I got my info from.

 

[jimmcld]

Try TM 9-2320-260-20 page fig 2-113,2-114, that is where I got my info from.

Your TM must be different from mine. In mine, those pages cover the electrical system.

 

[Earth]

I have 2 of these trucks. You pump it to bring up the pressure, start her up and get to work. The gauge reads zero after a bit and stays there. That's the way it is.

 

[jwaller]

the only way to have press on the gauge with it running is to leave it out with it running. then you get a reading. with it stowed you will not see a reading with it running.