electric fuel pump assist? (1 Viewer)

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I'm wondering if I am having sufficient fuel delivery problems with my 12HT. I have a Walbro(?) fuel pump somewhere and was thinking of maybe adding this before the fuel pump. Would this help with increasing fuel to the pump? Thanks.
 

Nz Nath

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Buy a cheap oil pressure test guage, if it comes with plenty of adapters you should be able to connect it to your fuel filter housing where the bleed valve/nipple screws in. If your pressure doesn't drop off under load then you probably don't have any fuel feed issues.
 
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Go ahead and fit the electric pump. if it resolves the issue then your factory lift pump is almost certainly faulty, and dissasembly, cleaning and repair is required.

I've never done a rebuild on a 2H/12HT lift pump, the two faulty lift pumps I've dealt with I've just replaced them with a known good second hand one.
 
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Here's an example of what I found on one 2H lift pump.. The engine had a small electric pump fitted when it came to me and it ran terribly when I removed the electric pump. No wonder...

 
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what size are the fuel pickup/lines on a HJ61 (12HT) and a HJ75 (2H)? are they the same or is the 12HT bigger?

They're identical..

The only difference with 12HT fuel plumbing is that the Injector Return line is plumbed all the way back to the tank. The 2H injector return line is plumbed back to the inlet of the lift pump.
 
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Currently running on front tank. Have not been able to replace the fuel pickup screen, as I was able to on the rear tank. When driving at constant 65mph it feels like I get hit by a 20mph wind for a second every 30seconds or so. When I get back home this weekend I will fill the rear tank and see if it does the same on the rear tank. I know that some who have swapped a 1HD into an 80 have run a electric fuel pump to help with fuel delivery. I do have 30% bigger injectors and the front fuel screw all the way out.
 
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Currently running on front tank. Have not been able to replace the fuel pickup screen, as I was able to on the rear tank. When driving at constant 65mph it feels like I get hit by a 20mph wind for a second every 30seconds or so. When I get back home this weekend I will fill the rear tank and see if it does the same on the rear tank. I know that some who have swapped a 1HD into an 80 have run a electric fuel pump to help with fuel delivery. I do have 30% bigger injectors and the front fuel screw all the way out.
I am having similar issues with my 12ht (fully rebuilt, Gturbo, 30+ injectors, modified injector pump). At 2500rpm it feels like I am getting hit by a headwind - like the engine is missing… it doesn’t happen all of the time.
Getting pretty frustrating! Trying a new Bosch primer this weekend to see if it is getting a bit of air in….
 
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I am having similar issues with my 12ht (fully rebuilt, Gturbo, 30+ injectors, modified injector pump). At 2500rpm it feels like I am getting hit by a headwind - like the engine is missing… it doesn’t happen all of the time.
Getting pretty frustrating! Trying a new Bosch primer this weekend to see if it is getting a bit of air in….
Let me know how it goes
 

Nz Nath

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If your injection pump has been in to a shop with the feed pump still attached, they definitely would have looked at the feed pump and rebuilt it if needed, I think the parts are only $50.
 
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Just be careful when fitting a lift pump, you want to use something rated for diesel and in the 5-7psi range and say 35gph. There are lots of pumps around that can do this...

An EFI pump could put out 90+ PSI which is too much for the diesel injection pumps.
 
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It could be air or your pump might just be sticking. My 70 had the same issue, at first i thought it was air as it would die under load. J removed the fuel lines to the pump and sprayed carb cleaner along with compressed air into it and that fixed it.
 
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Let me know how it goes
Well, it wasn’t the Bosch primer…. At 2400 rpm it is perfect, and at 2700 rpm it is perfect…. It just doesn’t like 2500 (which is spot on 100km/hr)
I am assuming now that it isn’t an air leak or fuel delivery problem as it is fine at higher revs…. Could one of the new 30+ injectors not be spraying properly at 2500?
 

Nz Nath

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Does it do it at cruise or when accelerating? Only at 100kph or at 2500rpm in other gears? If at cruise, what happens if you plant your foot whilst it's happening?

Mechanical Injectors are very simple, I don't see why one of them would be playing up at certain conditions, vs any other culprit.

I'd be looking at the screen on the feed pump inlet banjo, and the tank pickup for partial blockages.
 
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I checked the inlet screen to the feed pump yesterday and it was clean. I filled both tanks and will do some driving today on the rear tank to see if it still does it. Then drive some on the front again to see if it does it still.
 
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I/m back, drove about 110mi round trip. Switching tanks didn't seem to make much difference. But on the way home I noticed the boost gauge fluctuating when the engine seemed to be hitting a headwind. Hmm....might be time to start another thread :-(
 

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