I have a 1989 Dodge Ram Van B250 TBI 5.2L 318ci engine. It takes about 10-15 seconds of cranking to start the engine. After it gets hot sometimes it never starts. I'm getting afraid of taking it anywhere I have to trust it to start.

If I pitch a spoonful of gas into the carb while cranking, it instantly starts. If I short the outputs of the ASD relay so the fuel pump runs continuously and then crank the engine it instantly starts. I can see that fuel does not spray into the carb for quite a while after starting cranking, and it starts when the injectors start squirting fuel.

Why does the fuel take so long to get to the injectors? Does it siphon back down while sitting and take a while to get back to the carb? I'm wondering if air in the fuel line is why it behaves worse once hot.

I tested fuel pressure at the fuel pressure regulator at the carb and it comes up to 14 psi, but really slowly (taking about 10 seconds). Once up to pressure, it's solid and the pressure regulator dumps fuel back to the tank. Safety tangent: I tried to hold my thumb over the output of the fuel return line to see if it was misbehaving and when it came up to pressure, van started and fuel came spraying out like a thumb over a hose. Yowza! Won't check things that way again.

Anyhow, I checked pressure at the output of the fuel filter - and the input to the fuel filter (from the fuel tank pump). Pressures behaved the same as I measured at the carb, but replaced the fuel filter anyhow. I also pulled down the gas tank and replaced the fuel pump.

An ideas appreciated! The only thing I can think is the fuel is somehow draining back down from the carb when the engine quits - leaving air in the last 5' of line or so from the fuel filter. Deos that matter? Is the fuel regulator suppose to allow a backfeed of air or is it suppose to stop backflow?

 

Isn't TBI a return-style system?

I would suspect either the regulator is bad, or the fuel pump is on its way out. Gotta get creative to put a pressure gauge on it though, as I don't think there is a convenient schrader valve to hook one up to.

 

Yes, it's a return-style system. When the pressure at the regulator gets up to 14 psi, it starts bypassing extra fuel back to the tank (confirmed to work). This action works fine with my vehicle. I replaced the fuel pump and it behaves like it did before replacing the fuel pump. No Schrader valve, so I just unconnected fuel lines and watched the pressure from the tank pump, then from the fuel filter, then into the carb pressure regulator. All showed the same behavior... slow rise to 14 psi, and engine would start only after the pressure got up to 14 psi. I think the fuel injectors don't work below that pressure.

My best guess is that the fuel regular leaks air back ~into~ the fuel line somehow after the engine is turned off. Then to restart, the pump has to refill the fuel line before pressure can go up. There just isn't anything else in the fuel system to go bad. But how can the regulator leak air into the system? I'm hoping someone else has seen the same effects I'm seeing and can tell me how they fixed it.

 

I replied a content-ful email to HeyYou last night and posted it. Where did my reply go?

 

Maybe put the fuel pressure gauge at the fuel filter on the passenger side frame horn. You could so this without having to cut any hoses or take the air cleaner apart.

 

SteveR,

Yes, as noted in the original post, I checked fuel pressure by disconnecting hoses from the fuel filter and measured the pressure from the fuel tank and after the filter. They both behaved the same as the pressure up by the pressure regulator.

I also purchased a new fuel pressure regulator. Sadly, no change. This van now has me stumped. I have NO CLUE what to do next. I've replaced the fuel pump, the fuel filter, the fuel pressure regulator. Still, it takes about 10-15 seconds of cranking to get fuel squirting out of the carburetor body injectors. Uggh. I'd like to keep this van, but I just have to get this fixed somehow and I think I've checked and replaced everything.

Any help appreciated!

 

What brand fuel pump did you install?

 

I don't have my manuals with me but I'd assume there is a check valve somewhere to maintain pressure when the vehicle is off. Perhaps you could reinstall the pressure gauge, run the vehicle, turn it off, and watch for pressure drop over a given period of time.

 

SteveR,

I've physically inspected the entire path from the fuel pump (and new filter sock) to the filter to the pressure regulator to the fuel injectors. No check valve.

I could watch the pressure drop after I turn off the car. Sadly, I don't know if the pressure is suppose to stay high or slowly settle back. I know only that there was never anything (like a check valve) that is now missing. Nothing catastrophically failed. It just got worse and worse until I replaced the filter, then didn't fix, so I replaced the fuel pump, then didn't fix so I replaced the pressure regulator.

 

Rock Auto offered three compatible ones - a Spectra pump (80-123 psi), Airtex (70-95 psi), and Carter (12 psi). I ended up going with the Airtex E7018 pump and the Airtex FS148 fuel strainer. Multiple on-line sites indicate this is a match for the Dodge B250 series vans.