2000 DT-140 EFI Strange Fuel Problem at Idle

[Valvguy]

I have owned this motor for many years and it has been a great motor. This year it's doing something really strange. Pump the bulb and start the engine. It idles fine for about 10 minutes and then it seems to starve for fuel and die. Strangely enough if the bulb is pumped first and the idle is short before going WOT to get on plane - it will run at high speed all day long. What it won't do is idle for long or idle under load - as in pulling a shrimp trawl for very long. Pump the bulb and restarts fine but same idle problem. I've replaced the bulb, replaced the fuel filter assy, inspected and cleaned the fuel vapor separator and the cone shaped inline filter. Rebuilt the mechanical fuel pump. It appears that the Vapor Separator has fuel in the "bowl" when the engine quits. Fuel Pressure Regulator working correctly. Now......... about this electrical fuel injection pump. I noticed it leaking fuel from the "hat" end with the nipple. I would think that if that pump was the problem that this would get worse at WOT but it gets better? I'm stumped.

[jfwireless]

I had a similar issue with a 2004 DF140. I finally ran the engine off a temp fuel tank to rule out a fuel line to fuel tank issue and it ran just fine. Never saw an issue with the fuel tank fuel line , but replaced the entire fuel hose back to the fuel tank from the fuel separator and all was well again. So that fuel line must have small pin hole or something I just did not see.

Jim

[Valvguy]

I'll give that a try.

[Solarman]

When you cleaned the VST, did you remove the needle valve seat and inspect to see if anything was lodged on the backside of the seat (possibly fragments of the small clear discs from the low pressure mechanical fuel pump)? Usually this would affect higher rpms though.

Another thought, did you check out the TVS per the manual? If the TVS is sticking, not able to move freely, or not reading the right values then that could cause idling problems?

Any fuel leaking at high pressure pump is not a good thing.

Good luck, post back on what you find out.

[Valvguy]

Yes and I agree. I've found several postins on the Internet with the Exact same symptoms - but no fix. A guy named baldbob on this site had the exact same symptoms. Of course, the local mechanics act like they've never heard of this before. It's frustrating.

[Valvguy]

Here's an update....... We replaced the Electrical Fuel Pump Same thing. Finally got a set of fuel gauges . Installed the gauge between the upper manifold banjo bolt and the fuel pressure regulator Here's how this works. Key On the Pump runs for a couple of seconds at pressure reaches about 40 psi the Fuel Pressure Regulator is designed to "open" at 36 PSI thereby releasing fuel pressure back into the fuel vapor separator. and then closing at below 36 psi so that should keep the pressure at about 36 Mine works fine initially and then the regulator seems to malfunction. it relieves at 36 and is slow to or never reseats.