I think my fuel pump might be going out...

[Steeda90GT]

Recently, it's taken 4-5 attempts to start the truck. When I put the key in, and turn it halfway, I notice the fuel pump doesn't prime. It takes about 4-5 attempts to get it to prime, then when it does, the vehicle starts no problem.

So is the fuel pump going bad? Is there anything else I should check out?

 

[Lube]

Yes, you should check your fuel pressure at the fuel rail to confirm the diagnosis. Not sure what it should be for your truck, but on a 95 it should be 35-45 psi key on, engine off. It should be 30-40 psi with the engine running.

 

[Steeda90GT]

I'm assuming with a fuel pressure gauge? Any other tools needed? If so, where should I purchase them?

 

[Lube]

I'm assuming with a fuel pressure gauge? Any other tools needed? If so, where should I purchase them?

All you should need is the fuel pressure gauge with a fitting that screws on to the rail. It's a Schraeder valve fitting, just like on a tire. If you have a Harbor Freight near you, they have them. If not, any parts store should be able to hook you up, but HF will be cheaper.

 

[rego]

Sounds like a pump problem to me. Fuel pressure may be good after the pump gets spinning but getting it to spin could be the deal.

 

[drdoom]

All you should need is the fuel pressure gauge with a fitting that screws on to the rail. It's a Schraeder valve fitting, just like on a tire. If you have a Harbor Freight near you, they have them. If not, any parts store should be able to hook you up, but HF will be cheaper.

Ford may require an adapter, they use a Schraeder looks like a tire valve, but is a little smaller.

 

[Steeda90GT]

Gotcha. Now, what will the FP gauge actually tell me? When the fuel pump actually does prime, the vehicle starts up no problem and runs beautifully. When I dont hear a prime, nothing at all. So Im assuming that it will either have good, normal pressure, or nothing at all.

Maybe an electrical component is going out? (Fuel pump relay, fuel cut off switch, etc)

 

[Lube]

Gotcha. Now, what will the FP gauge actually tell me? When the fuel pump actually does prime, the vehicle starts up no problem and runs beautifully. When I dont hear a prime, nothing at all. So Im assuming that it will either have good, normal pressure, or nothing at all.

Maybe an electrical component is going out? (Fuel pump relay, fuel cut off switch, etc)

When you turn the key on, you should see pressure start to build nearly instantly. And it should get up to the 35-45 reading in a couple seconds. It's not doing that, which is why it's hard starting and requiring several tries.

 

[Steeda90GT]

When you turn the key on, you should see pressure start to build nearly instantly. And it should get up to the 35-45 reading in a couple seconds. It's not doing that, which is why it's hard starting and requiring several tries.

Right, I understand this concept. 50% of the times the fuel pump isn't even priming when I turn the key on. I don't need a gauge to tell me that there won't be 42psi.

So now, why is the fuel pump not priming when I turn the key on?

 

[yavapaires]

Right, I understand this concept. 50% of the times the fuel pump isn't even priming when I turn the key on. I don't need a gauge to tell me that there won't be 42psi.

So now, why is the fuel pump not priming when I turn the key on?

I don't think anyone can sit here and tell you that. That is something you will have to check out yourself. Get a wiring diagram and check the relays and the electrical connections. You might try pulling the wire off the tank and cleaning it. Try pulling the relays and cleaning them. Use electrical contact cleaner for best results.

 

[Steeda90GT]

That is pretty much what I had in mind. I was just wondering if these trucks are notorius for certain part failure. I will forgo getting the FP gauge and just concentrate on checking all of the electrical connections.

(I know some of the older Fords were notorious for having bad fuel cut off switches)

 

[Steeda90GT]

UPDATE: It only seems to happen when it's really cold out. On the warmer days, there's virtually no issues with fuel pump prime/startup.

 

[Runnin'OnEmpty]

Steeda, how many miles on the 99 Sport? If it's over 150K
or so, the pump might be wearing out.

My bet is on a faulty fuel pump. There's a technique of
cutting an access hole in the floorboard to change it
without having to drop the tank.

Another quick and easy thing to check is the fuel pump relay.
Try exchanging it with one of the other relays in the box as
a test.

 

[Steeda90GT]

Where is the FP relay located? Also which one is interchangeable with it?