what pressure reading should there be on a 1989 f150 high pressure fuel pump.

Asked by mclemob Jun 20, 2010 at 03:50 PM about the 1989 Ford F-150

Question type: Maintenance & Repair

What direct pressure readings should i be getting on a high pressure fuel pump (rail mounted)?  I am reading 17 psi.

What should the pressure reading be when hooked  up to the schrader valve on the fuel line just behing the engine up close to the firewall?  I read 10 psi

Are these within spec's for1989 F150 4.9 L EFI high pressure fuel pump?.

7 Answers


You should have 45-60 psi at the rail with engine running.

15 people found this helpful.

yes you are withen spec,s,if you are getting to much or not enought fuel,put a fuel regulator on it,you will be able to adjust the fuel pressure.

4 people found this helpful.

that sounds kinda low. i have an 05 f150 and my fuel rail pressure is at 40psi. but mine is the 5.4 triton. but that dose seem low.

9 people found this helpful.

On my 89 F150 5.0 2WD XLT extended cab with " key on " and with " motor off " at the rail I get 43 PSI, when running 37 PSI. They say to pull the vacuum line off the fuel regulator at some point to see if it shoots up another 5 to 15 PSI. If it does the regulator should be good to go. Also if there no gas in that vacuum line, if there gas the regulator needs replaced. That 43 and 37 PSI was with it not up to normal driving temperature,I guess that matters. I will have to check it again. I read somewhere else it should be between 43 - 45 PSI. I also read anything above 30 is OK. I'm having uneven idle problems with a little jerking when over 35 MPH and I have a small miss, ( appr 150,000 miles on it.) I'm leaning towards my " pickup coil " within the distributor is going bad. You would think it was my EGR valve by the way it floats back and forth a little when over 35-75 MPH. I already replaced most of the other parts. You would also think the fuel pressure or the pump was going bad. If you ever get some jerking when you start off and when right after you let off on the throttle, that would be your " intake throttle sensor " that's mounted on the front bottom of the intake. I had one go bad on me. I'm here at this site to see if 37 PSI is good enough, I'm down to it's either the fuel pressure ( fuel pump & whatever ) or the " pick up " coil inside the distributor or those 2 check valves with the " diverter " valve behind the intake. Just follow the hose off the smog pump it will lead to to them. I was getting " code 44 " for the ( Thermactor smog system.) That ended up being a broken vacuum line within that smog system. So in closing, I have uneven idle at times, a small miss and when over 35 to 65 MPH it floats back and forth a little like it's the EGR valve. I'm leaning towards the " pick up " coil within the distributor. When replacing your distributor ( 89 f150 5.0 ) some have a thicker shaft, most if not all of the " new " replacements don't come with that added on sleeve or spacer, that I think keeps it from moving around from side to side down in there. I tried one of the other types it didn't sound good at all. If you are going to replace your distributor, I would at least pull it to get some pictures of it or just take it with you to the part store. I think that added on sleeve might matter if that is what you have your 89 F150 5.0 distributor. It's pretty much impossible to buy a brand new distributor with that added on sleeve. Maybe it doesn't matter, but I think it does. You should ask about that. Since I can't replace the " pick up " coil on my own, that top part on the distributor is pressed on. I'm off to try to find a Ford rebuild distributor with a brand new " pick up coil " that has that added on sleeve on the shaft, wish me luck. You don't see any at Ebay, Amazon and most other sites, all are those thinner shafts that are missing that sleeve.

2 people found this helpful.

It ended up being the rear fuel pump or the fuel pump strainer and my catalytic converter was starting to clog. After replacing those I know longer have that floating back and forth above 35 MPH. I did replace the pickup coil within the distributor, that wasn't it. I also started using 89 octane gas instead of the 87 octane, it does lift the idle speed. My sister husband pressed out the distributor to change the pick-up coil, I kept my original distributor with 150,000 miles on it. I no longer has that miss since I sped up the idle by switching to the 89 octane gas. I did remove the front fuel tank for good, now there's a lot more open space under there. All you have to do is plug off the gas lines that connected to that tank. I can now get to it if something needs repaired under there. Of course having only one tank gets you appr 320 miles, but who needs two tanks most of the time. I also changed out most of those plastic vacuum lines with rubber lines. That was pretty easy, you will need appr 50 feet of hose and 2 " T " to split two of the lines. Leave the plastic ones on, just disconnect them. So you can see what went where, then you can remove them. You don't need to remove any parts to get that harness off. I needed closer to 40 feet, so purchase 50 to be sure. And at least two of the lines are larger diameter, but you really don't need to change those two out. Those would be the two that connect to the manifold. You'll see once you get there. Later I blocked off the EGR valve by placing a piece of sheet metal in between instead of the gasket and I replaced the timing chain. It runs like it's brand new with 150,000 miles on it. It was impossible to locate the right EGR valve for it, they don't make that part number any longer. Here's a picture of my 89 F150

4 people found this helpful.

I read anything above 31 pounds at the rail up to 45 is where it should be. I replaced my original pump with a Napa replacement, but it's not the same wiring connections. You have to butcher your original connecting wires, so make sure you purchase the bosch fuel pump. It's a little higher pressure and its the original wiring. It also depends on your fuel pressure gauge, my gauge reads 4 pounds off compared to the better ones. So when I say I have 33 pounds at the rail, I really have 37 pounds.

2 people found this helpful.

Do you have to use a internal tank pump? Can I put one in the line And regulate it as in the carb days??

1 people found this helpful.

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