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My truck has 223k on it and I don't think the fuel pump has ever been replaced. So I thought a I would change it on my terms and eliminate the where & when it would go out. I bought a Bosch #69136. I rebuild the FPR about 20k miles ago when I rebuilt the fuel bowl and at that time I installed a schroeder valve in the post filter port of the fuel bowl. For the 20k my fuel psi has always been between 62-65psi even with a dirty filter & hutch was done about 30k ago.
Correct me if I am wrong but isn't the post filter port on the right side under the drain valve?
Today before removing the old pump I put a gauge on it and it is a steady 72psi. I replaced the fuel filter about 5k ago also.
I know that 60-65psi is about where the fuel psi should be but what is the max fuel pressure you want to have ?
Also what could cause fuel pressure to raise even with an old pump ?
Because I am sure that this new pump is going to make my problems worse.
I am thinking since I'll have the fuel drained down I'll check the filter and the fuel bowl stand pipe.
What else should I keep in mind???
I hope it isn't the FPR messing up after only 20k.
Can you take the FPR apart and clean it without replacing the seals or O ring?
Yes, the post filter port is on the passenger side of the bowl just below the yellow drain valve. In the picture below it is on the bottom right and labeled fuel bowl plugs.
I don't think there is a "max" pressure really that you should guard against to avoid damage. As I understand it, excess fuel simply gets routed back to the tank and I would not suspect that 72 PSI would cause any damage or ill effects on the truck running.
I believe that the spring in the FPR is what causes the FP to rise and fall based on the tension or how it is set in the housing. The pump is simply on or off, there is no pressure setting or anything on the pump, the FPR does all of that for it.
If I were you, I would not worry about the 72 PSI because you are well above the minimum and just above the normal reading.
Yes, the post filter port is on the passenger side of the bowl just below the yellow drain valve. In the picture below it is on the bottom right and labeled fuel bowl plugs.
I don't think there is a "max" pressure really that you should guard against to avoid damage. As I understand it, excess fuel simply gets routed back to the tank and I would not suspect that 72 PSI would cause any damage or ill effects on the truck running.
I believe that the spring in the FPR is what causes the FP to rise and fall based on the tension or how it is set in the housing. The pump is simply on or off, there is no pressure setting or anything on the pump, the FPR does all of that for it.
If I were you, I would not worry about the 72 PSI because you are well above the minimum and just above the normal reading.
Nice photo and yes I did use the port below the drain which is post filter and the port on the left is prefilter if I recall correctly. So insteady of going any farther with the fuel pump I took it off jack stands so I could drive it up and down the highway to check to make sure the up pipes don't leak this time.
Little more testing but I do believe I have my up pipe issue resolved.
I also put the fuel psi gauge back on it when hot and it is a solid 72psi. So you don't think 72psi is above max pressure. I am on the fence about how high it should be.
Originally Posted by woodnthings
Fuel pressure is determined by the FPR and can be higher If the poppet is sticky. That could be the cause.
Ken can you take the FPR apart and reuse the oring or do you replace them everytime you take it apart ? Would you think if I am having a issue with the new poppet after 23k I might have a issue with the fuel itself ? Maybe the truck stop I get fuel at got a bad batch? Both the Bf1212 and the bowl filter were replaced 5k ago.
What would say is max fuel psi at idle?
If it bugs you that the FP is around 72 PSI then you should look into it and try to correct it. If it were me, I would just leave it because the extra fuel is just getting routed back to the tank anyway if I understand the system correctly.
I don't think you will harm anything in the engine at that psi; however, you will be placing an extra burden on the fuel pump unnecessarily by asking it to maintain the extra pressure which can lead to early failure.
This causes heat so then it becomes a cooling problem which depends upon the amount of fuel used, the amount being returned to the tank, and the temperature of the fuel. Imagine being below a quarter of a tank of fuel in the summer time. How much cooling of the pump gets done will be determined by the temperature differential between pump and the fuel in the tank. The lower the fuel level, the faster the heat builds. Supposedly, the fuel can get up to 170*+ F in the right situation: low fuel, idling after hard run/tow, low cruise speed..fuel flowing through the heads with a RR, etc.
Opinions will differ....
I keep FP between 55 and 62 psi. Nothing is gained by having it above that.
Thanks guys for all your input !
Well I am not pleased to see 72psi but I think I'll live with it for now even though I have a road trip coming up and I am out of funds for parts. So here is what I am thinking I over looked. Up until about 6 mths ago I used the same pressure gauge I have for years and the old schrader valve on hose went bad. The cost of the hose alone was $15 and I found on Fleabay a cheap kit that had new hoses & gauge. It might that be that the cheap gauge is wrong. Today I'll put my old gauge on and see what it says. Also until I figure out what is going on I am going to put off installing the new pump.
Now I'll have spare pre & post pump filters, fuel bowl rebuild kit and a fuel pump for the road trip if need be.
I concur with you jhl3 about fuel temps and I myself don't like running below 1/2 tank. I believe there is alot of truth in your statements. I am a firm believer fuel pumps last longer with cooler fuel and at less psi of demand. I learned these lessons back in the 90's with my 2.3 Turbo Coupe where I did everything wrong and in 80k miles that car eat 3 fuel pumps in the tank and 2 frame mounted pumps.
All because I was young and dumb, that and I didn't look at the fuel system as a whole.
I have a habit of letting something simple turn into more than it needs to be. What I mean is "One things leads to another" or if I am replacing or repairing one thing I may as well replace this since I am right there. So if I am going to dig into the FPR I may as well install a FXR and at that time or before I want an actually fuel pressure gauge in the truck. That way I will have done the complete fuel system.
Well yesterday I installed the new Bosch fuel pump and changed the bowl fuel filter even though it only had 5k on it.
It didn't change anything I am still at 72psi. So at least the new pump didn't make things worse.
Next month I am going to try to ear mark some cash for fuel psi gauge in the truck.
The old pump was the OEM pump made in Germany the new pump was made in the Czech Republic. So I guess German's are losing jobs like we are here in the USA to outsourcing. Hopefully this pump will last as long. Mind you the one I took out was working and had 223k and is still good as a backup pump.
Up until about 6 mths ago I used the same pressure gauge I have for years and the old schrader valve on hose went bad. The cost of the hose alone was $15 and I found on Fleabay a cheap kit that had new hoses & gauge. It might that be that the cheap gauge is wrong. Today I'll put my old gauge on and see what it says. Also until I figure out what is going on I am going to put off installing the new pump.
