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Discussion Starter #1
My 1989 B250 Ram Wagon with TBI 5.2L V8 takes about 10-15 seconds to start even though it turns over fine - the effect is worse when warm to the point that I almost killed the battery one time.

I've checked spark plugs, distributor and ignition coil. All look fine. When I start the engine cool I can see fuel spray onto the butterfly valves in the carburetor bodies. When I start warm, there is no fuel spray for up to 15 seconds.

I measured the fuel pressure at the carburetor, into the fuel filter (from the tank), and out of the fuel filter. All behave about the same. When I turn the ignition on, I get a bump up to about 3-4 psi and then back to zero. When I start cranking, it slowly rises to about 14 psi during 10-15 seconds. Only when the pressure gets high do the injectors spray. Just to confirm, I tossed a teaspoon of fuel into the carburetor immediately after starting crank and the engine fires up wonderfully each time.

It's a fuel problem. What is causing this? Shouldn't the pressure just go up to 14 psi when I turn on the ignition (before crank) and just stay there? What makes the pressure go away when just the ignition is on? Why does it take 15-20 seconds for the pressure to rise when I'm cranking? All behavior is the same with the vacuum line removed from the pressure regulator, or with a vacuum manually applied to the regulator.

Help?

More detail at external URL I can send you.
 

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All those low fuel supply symptoms and not once have you considered the fuel pump to be bad?
When I turn on the ignition, the fuel pressure comes up to specified pressure. That makes me think the fuel pump is okay. It's just that it doesn't ~stay~ up at pressure.
 

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All those low fuel supply symptoms and not once have you considered the fuel pump to be bad?
Replace your fuel pump that should fix it wverything points to it
When I turn on the ignition, the fuel pressure comes up to specified pressure. That makes me think the fuel pump is okay. It's just that it doesn't ~stay~ up at pressure.
 

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It may build pressure but initially but it needs to hold it that is symptoms of a weak fuel pump it can start strong and wear down in a figure of speech and not put out enough to run correctly
 

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When I turn the ignition on, I get a bump up to about 3-4 psi and then back to zero. When I start cranking, it slowly rises to about 14 psi during 10-15 seconds
You should have full pressure a second after you turn the key to on.
 

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Discussion Starter #9
You should have full pressure a second after you turn the key to on.
Moparite, Thank you. Yes. I do have pressure for about a second after turning the key on. The problem is the pressure "spikes" and then goes away before cranking -- and then comes back really slowly.
 

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Discussion Starter #10
The PSI need to be around 14 and stay there for the engine to run correctly.
Alloro, Well yes, I know the pressure needs to stay at 14 psi (the injectors appear to work only above 12 or 13 PSI). But that's the problem I'm asking about!

If I turn on the ignition, it's confusing me why it jumps up fine, then drops to zero. And then when I crank, it builds up so slowly.
 

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Discussion Starter #11
It may build pressure but initially but it needs to hold it that is symptoms of a weak fuel pump it can start strong and wear down in a figure of speech and not put out enough to run correctly
Dylan, you're saying the fuel pump could be "half dead"? Hmm... Once the pressure does get up to 14 psi, the engine starts fine and never has a problem. In fact, once the engine runs for a second or so, excess fuel starts coming out of the pressure regulator and returns to the tank.

In other words, it runs fine long term. The problem is the first 15-20 seconds that takes so long to build pressure when I start cranking. I want it to "jump up quickly" like when I turn on the ignition.

I've never removed a fuel tank to access a pump. It looks like I might have to in order to figure this out. The hangar straps require a 9/16" socket that is about 4" deep (which I don't own yet). And lots of rust.. I see a broken bolt or strap coming on. Lots of wires and tubes are coming out of the top of the tank. Uh.. I really didn't want to do this unless I *knew* it was the problem.
 

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Fuel tank is easy to remove soak the bolts on the strap in oil or an oil based liquid dont use wd 40 because it dries let them soak for 10 mins or so and the bolts should come right off, as for the hoses on top they are just clamped on and pull right off it is about a 45 min job
 

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Discussion Starter #14
Fuel tank is easy to remove soak the bolts on the strap in oil or an oil based liquid dont use wd 40 because it dries let them soak for 10 mins or so and the bolts should come right off, as for the hoses on top they are just clamped on and pull right off it is about a 45 min job
Thanks for the encouragement. I figured more out today. Turns out the ASD relay turns off the ignition coil and fuel pump about a second after turning on the ignition - unless/until the crankshaft sensor shows rotation. So that's what was killing my fuel pressure.

I hot-wired the relay output with a jumper wire so the ignition and fuel pump could not turn off. Cranking the engine gives an instant start. Turns out the fuel filter sock must be plugged bad or the fuel pump is very worn making my fuel pressure rise very slowly. Either way, fixing it requires the fuel tank to come down.

I need a ~more~ than 3.5" deep socket 9/16" to get the nuts loose on the 3 hangars. How else do people get the nuts off? There is no room to come at them sideways with an open end wrench. On the other end of the hangars, it looks like they twist up into a long skinny hole. Maybe that side of hangars doesn't need to come down.
 

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Im glad you figured something out, im sorry i couldn't help you better its hard to diagnose over the internet without personally accessing the problem in person
 

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Discussion Starter #18
Thanks for the pointer. Turns out I already have ratcheting box end wrenches. These through-sockets have the same sort of thing driving them. The problem is I can't get a sideways position for the ratcheting wrench or a through-socket drive handle.

I need to use a double-deep socket to get the drive location down in the clear. I'm thinking I might have to cut a socket in half and weld the ends on a section of pipe. Or maybe cut two deep-well sockets and weld them together end to end.
 

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Discussion Starter #19
As for the nuts on the hangers, can you take some pics so i can see exactly what you are dealing with?
Got back too late tonight. I'll take some pictures tomorrow. I did get most of the fuel drained (filled up wife's car). I disconnected the tank fuel line before the fuel filter and put a hose out to a 5 gallon gas can.

I disconnected one side of the ignition coil (so the battery drain wouldn't be too much). Then I shorted the ASD relay wiring harness to mimic the relay closing. This made the pump come on and it happily squirted fuel into the 5 gallon test. It sure seems to work...

While doing this, I again tested the pressure. It does come up to 14 psi. It just comes up slowly - about 7 seconds. I wish I knew what a new pump could do. I hope I'm chasing the real problem.
 

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It seems to be the problem a new pump will jump the pressure up relatively fast and hold the preasure while vehicle is running and using fuel
 
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