1HDT fuel level effect on feed pump (1 Viewer)

Joined
Nov 3, 2008
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1,146
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Winnipeg, Manitoba, Canada
Yesterday after work I had a hell of a time getting my 1HDT started. Normally I manually glow for about 10 seconds (it's cold here) and crank with the skinny pedal on the floor. It takes a couple tries when ambient is really cold. Symptoms seem to indicate no fuel.

Anyway, yesterday I drained my batteries trying to get it to start. I had to keep getting out and pumping the primer like mad before cranking. After doing this about 15 times (and getting a boost), it started.

It dawned on me that I had low fuel in the tank - below 1/8. I filled up on the way home and it has started as usual ever since. I've been having fuel problems all winter with some improvements after replacing the fuel hoses and clamps. I'm thinking the feed pump is very weak, and even worse when it's cold.

So my question is: would a low fuel level in the tank have an effect on a weak feed pump not being able to suck fuel from the tank? The weight of a full tank of fuel should in theory provide a bit more "pressure" on the fuel lines. I'm not familiar with the fuel suction inlet, but I would assume that it would still be submerged even with a low fuel level. The tank was not empty.

Any thoughts on this? I haven't quite been able to correlate truck front-to-back slant on my starting problems. But it would seem that a nose-down attitude would gravity feed the fuel much better than nose-up. Maybe the same kind of scenario as a near empty tank? In all my investigation into my cold start problems, I had not taken into consideration fuel level. I am using winter diesel and antigel. Maybe there's a problem with the inlet?
 
Joined
Sep 28, 2002
Messages
8,020
Location
Kamloops, BC Canada
 
 
 
 
Frozen fuel lines, fuel gelling, water in fuel lines (freezing and blocking), leaking pump/lines/filter - air leak.

Bad batteries - if you still have the Japanese batteries in there, get rid of them NOW. 95% of the ones I have tested are junk.

Glow system not working properly. Timer, glow plugs, weak batteries... not glowing long enough, no post-glow.

These units should start right up with no problems if all is right...

~John
 
Joined
Nov 3, 2008
Messages
1,146
Location
Winnipeg, Manitoba, Canada
Frozen fuel lines, fuel gelling, water in fuel lines (freezing and blocking), leaking pump/lines/filter - air leak.

Bad batteries - if you still have the Japanese batteries in there, get rid of them NOW. 95% of the ones I have tested are junk.

Glow system not working properly. Timer, glow plugs, weak batteries... not glowing long enough, no post-glow.

These units should start right up with no problems if all is right...

~John
Thanks for the response. The main problem here is that I bought the truck in November and it's been far too cold to really do a proper diagnosis. Pretty tough to hold a wrench when it's this cold. I have made incremental improvements though.

I religiously use an antigel whenever I fill up. And the lines have been emptied a few times so I don't think there's water in them. Each time I've drained the filter there has been nothing but diesel. My bet is on an air leak somewhere aft of the firewall. I'll check the rear fuel lines, tank inlet and hardlines when I install my electric fuel pump.

I hear ya on the batteries - mine are the Japanese ones. They are performing decently so far, but I'll replace them soon.

As for the glow system, I used to get about a 2 second glow light illumination even when below -30°C. I'm now manual glowing, and manually afterglowing (still talking about cars here :grinpimp:). Glow plugs all checked out fine, so I've ruled out the glow system.

Cheers!
 
Joined
Sep 28, 2002
Messages
8,020
Location
Kamloops, BC Canada
 
 
 
 
They will often hold a charge for a few days or so, and then not have enough jam to get you going when it's cold or they've been sitting.

Have them both load test and inductance tested. Don't put AGMs in it when you replace them, use the Napa Group 27C6 or equivalent (anchor bonded plates to resist vibration).

~John
 
Joined
Jul 22, 2003
Messages
18,034
Location
Perth Western Australia
 
 
 
Any thoughts on this? ?
Yes ,the fuel should remain in the lines overnight regardless of the fuel tank level if it was running when you switched off the engine.
You should be able to disconnect the fuel line at the pump and have fuel run out.
I would check this BEFORE starting in the morning.

If the feed pump is shagged ,then so will the rest of the pump.

The filter head/cap can be bought for $75 from roodogs
 

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