Engine/Transmission (1994 - 1998) Help!! Replaced the OF Valve But Now.....

[biggy238]

But now my pressure is spiking with the RPM.

I have a leak somewhere near the fuel filter that i'm going to tend to tomorrow sometime.



I think this indicates a blocked return line but I have no Idea on where to start to actually diagnose it or where to look first for a blockage. What could even have caused something like that?



I need help before it spits my fuel filter off like shrapnel.



Thanks for helping.

Kyle

 

[DBraunig]

kyle, your pressure should spike with rpm... 18 psi at idle about 30 psi @ 1500 rpm or so. that metal line the overflow fits into turns into rubber behind the fuel filter and down that back of the engine and then turns to metal again near driver frame rail. rubber line is probably leaking. you may have moved it around a little when you put the overflow in and didn't know it. check that line. its real bad about dry rotting and causing hard starts, white smoke, stuff like that. i always use EFI hose when i replace it, not because it needs the pressure but it seems to last longer than cheap fuel hose.



Dave.

 

[bmoeller]

Fuel Pressure: 18-24 psi at idle, 28-36 at 2000 rpm with no load.



Do you have snubber or needle valve to steady the needle on the gauge?

 

[biggy238]

Well... . It'll be tomorrow before I can check the hose.



Bmoeller: I think you are closer to the problem. I came home at 11pm and took it for a spin, hoping nievely that maybe it had righted itself. The pressure was at 75psi (on a 73 psi sending unit) which outraged me. I brought it home and hit the petcock on the filter. There wasn't 75psi even with the motor running. Thats why I can't find the leak right at the moment, I sprayed fuel everywhere. On the other hand, I think maybe one of the first pressure spikes killed my sending unit. I thought at first maybe it had shaken itself until it broke free from the ground it had. (causing infinite resistance and pegging the gauge) I checked that and checked to see if it had 75psi at the sender. Not a chance. It didn't even lose fluid until I completely removed the sender from the line. I pumped the transfer pump three times to make sure it wasn't just all air and sprayed myself in the face. They move alot more fluid per stroke than I expected (guess I needed it) I didn't have a valve on it to snub it. IT's a dakota digital gauge with a VDO sender that is processor controlled (leveled) so the pump surge can't be seen. I just was in hopes I wouldn't need the valve inline. I guess I do. I'm going to see about sending the unit back under warranty and replace it. Sorry I got excited about having a blocked line (i'm still gonna check it though). With the kind of week i've had I just assumed it to be the worst scenario. Thanks for the help guys. And never take things (or yourself) too damned seriously.



Kyle

 

[Joe G.]

Kyle,



You have to have the needle valve or the pressure spikes will tear stuff up. Close the needle valve and then open it so the gauge barely works.

 

[biggy238]

Yeah. I had seen you and others post that long before I even got my gauges while I was still shopping. I was being hard headed. Thanks for the sound advice as usual Joe.





Kyle

 

[ABorchard]

I went though four VDO senders before giving up and going with mechanical setup. They only lasted between 10 seconds (no needle valve) and 5000 miles all with a needle valve.



The electric gauges work great on a 24 valve but on a 12 there is too much pulsation even with a needle valve or snubber. The way three of them failed gave a false sense of security, they only read the highest pressure they had seen and zero with no in-between.

 

[biggy238]

I've gotten about 4000 out of this one. I have an 18" grease gun hose and a 45* fitting at the pump which helps take out some of the shock I think. They have another gauge and sender ($80 for the gauge and 124 for the sender) that will supposedly survive it. I guess i'll try this again with a needle valve until I can afford the new gauge. Although, while this one was working it seemed very responsive. It responded to engine load as quickly as the grade or throttle changed. Oh well.



Thanks again,

Kyle

 

[FATCAT]

I have a Diprocal Boost pressure guage as my fuel gauge and it has worked great for over a year and 25K miles. All I did is drill out the banjo bolt to used in the fuel pump (bought a spare just in case), and taped it with a 1/8 NTP tap. screwed in an 18" grease gun hose, then a needle valve, then connected the whole thing to copper tubing. I have a few turns or coils in the copper tubing before it goes through the firewall, then right into the guage. I have the connection at the gauge REAL tight so it won't leak.

I have no spikes and the needle hold steady and climes and falls just like a your speedometer. Great setup and cheap.