Engine/Transmission (1994 - 1998) Engine bogs, low torque

[RWW]

In last few weeks engine takes too long to crank and wants to stall on take off. 1997/3500/5spd/260k. Other related symptoms. . will stumble and vibrate like fouled injector at times. Could not accelerate over 60 mph on another occasion. next day no problem. Dealer changed fuel filter, reset idle, checked fuel pressure. Found no leaks or other causes. Problem persist, just not on their watch. Has always cranked immediately even in 0-10 degree weather now has trouble in 40-50 degree.

 

[fest3er]

The engine needs three things to fire: fuel, air and compression. Disrupt any of them and you get a rough engine. Since it can run well, compression and air are not the problem. That leaves fuel.

Too long to crank means it's got no fuel, which likely means it is draining back to the tank. You may well have a pinhole (or larger) in a fuel line or hose. If your nose detects any #2 oil under the hood, you'll have lines and hoses to inspect:

• return hose behind the fuel filter
• hose between lift pump and pre-screener
• hard lines from engine to firewall
• supply and return lines at or near the quick-connect fittings

If you see wetness that smells like #2 oil, the problem is most likely after the lift pump (including the return line). If it's nearly undetectable, suspect the lines before the lift pump. Also check the fittings on the pre-screener; they've been known to let air into the fuel if they aren't tight enough.

Check for related threads in the past 3 months or so. This was covered recently.

 

[RWW]

Thanks, sorry taking so long to respond. Have looked everywhere. . no luck yet. Need to pull bed to put new sender in tank so will do a thorough search then. Problem IS getting worse though. When it runs great it runs great but will mush down to 45mph or so after a while. Could have clogged screen on meter. This a great sight. Have solved several problems on 2005/3500 just by reading through the posts. Richard Wheeler

 

[fest3er]

Another trick (if your hearing is still good): wear earplugs, run the engine until it's about as smooth as it'll get. Open the hood, shut it off, stick your head in near the master cylinder and pull the earplugs.

If you hear a hissing/burbling/air-ish sound, you've a holed fuel line.

Yes, my hearing is still fairly decent. While I was having troubles with my '98, I was hearing an air-ish sound from that general vicinity after shutting the engine off. And that was without using earplugs. In my case, it was a large-ish hole resulting from 12 years of rusting.

 

[Wingate]

If you have the time... . remove the line from the transfer pump and drop it in a bucket of fuel. Start the truck, allow it to run long enough to ensure you have no air in the system from connecting the temporary line.

Shut the truck off, let it set over night, see if its easier to start the next morning. Atleast you can determine whether or not its under the hood or under the bed.