Engine/Transmission (1998.5 - 2002) FP too high again

[Rockcrusher]

Same problem as Dan. When I first installed Genos sending unit and Westac gauge everything seemed to work fine; 12-14 psi and then started reading over 20. Called Andy at Geno's and he said sounded like failty sending unit. He sent me a new one and it does the same thing. Rechecked all electrical wiring and seems to be ok. Can computer be sending too much voltage to pump?

Could the return line from injection pump be blocked? How much pressure can the lift pump actually put out? Is it positive displacement?

Going to get mech gauge today to check direct.

I have sender connected to Schrader valve.



Strange thing happens when I disconect wire from sending unit, gauge wants to peg backwards (with power on)

 

[illflem]

I went though three senders before I gave up and went mechanical. Worth the peace of mind knowing that your gauge is reading right.

 

[Rockcrusher]

Originally posted by Rockcrusher

Same problem as Dan. When I first installed Genos sending unit and Westac gauge everything seemed to work fine; 12-14 psi and then started reading over 20. Called Andy at Geno's and he said sounded like failty sending unit. He sent me a new one and it does the same thing. Rechecked all electrical wiring and seems to be ok. Can computer be sending too much voltage to pump?

Could the return line from injection pump be blocked? How much pressure can the lift pump actually put out? Is it positive displacement?

Going to get mech gauge today to check direct.

I have sender connected to Schrader valve.



Strange thing happens when I disconect wire from sending unit, gauge wants to peg backwards (with power on)

Went to Hose Mart and got hose fittings and gauge. $9 for hose and fittings and $11 for good 0-30 gauge.

Disconnected fuel line from schrader valve for test. Replaced hose and readings were normal 12 psi. Wierd!!!:--)

 

[illflem]

Sounds like a poor ground.

 

[mikel]

So far I've killed 3 senders on my Dakot Digital gauge the same way. They just start reading higher and higher pressure at idle, but seem to work fine running down the road. Mine are mounted to the fender and have an 18 inch hose going to a tapped banjo on the vp-44. I think the vp-44 makes high pressure pulses in the fuel system at idle and this is what kills the senders and probably the lift pumps as much as anything else.



Good luck,

Mike

 

[rweis]

I put a needle valve on a T block in the fuel line (got this idea from Bill Flemming), put a 18" line on that and put the sensor on the end of that. Turn the needle valve all the way to off, crank 'er up, turn the needle valve open just enough to register pressure, tighten the needle valve packing so it doesn't move.



IF you have a leak it will be a minor drip. The needle valve snubbs the pressure fluxuations. The 18" line further reduces the pressure fluxuations.



I do Westach solid state sensors. 6 months so far so good.



Good Luck,



Bob Weis

 

[HeberRam]

Go mechanical

My recommendation, if it matters is, go mechanical on all your gauges. There is enough electronic crap on our trucks as it is, and can't afford second guessing if the darn gauge is correct!!!



Steve

 

[OL RATLR]

FP to high again

Go mechanical no more problems. Oo.

 

[Rockcrusher]

I agree, its time to go mechanical. If I dissconnect the hose and the reconnect, it works right for awhile and then goes crazy again.

I thought maybe the 'relief' was sticking closed but relieving the pressure on the hose lowers the pressure as I said. Valve in schrader valve must not be releasing properly. I have the hose connected to schrader valve. Hose does have pin inside to open valve.

Wierd.

 

[Dane]

I'm gonna guess that it's the way the computer pulses the lift pump at start up confusing the sender? Anybody know how these electronic senders make up their mind as to pressure? Does the ecm send out pulses to the lift pump other than at start up?