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nissan
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Discussion Starter · #1 ·
I have been reading on the Bosch VE pumps, it seems the signal for the rpm dependant timing change comes from the vane pump pressure. As the revs rise, the vane pump pressure increases, changes the position of the roller that the cam plate runs on. So; will fitting a lift pump trick the IP to operating at full rpm advance all the time? Is this where the change in "feel" of the responsiveness of the engine often mentioned comes from?
 

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it will effect the timing to a degree. however if the lift pump pressure is low its not going to change it a lot. the other thing thats been mentioned that the injection pumps are setup with a few psi of pressure on the inlet anyway, then you fit it on a motor that doesn't. not sure how that works out.

the best thing about lift pump is it stops air being sucked in by the injection pump.
 

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nissan patrol gu 4x4
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My thoughts: pressure supplied to the vane pump will not be the same as what comes out of the vane pump unless fuel can bypass the vanes. As the vanes only spin at the same speed as the injection pump, the pressure supplied to the injection pump will be the so close to the same , it would make very little difference if any.
 

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The nutty professor
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well my car seemed a bit sluggish for the last couple of months and it was blowing black smoke at higher rpms where it never used to , i ended up pulling out the holley red lift pump that i fitted and pulled the base plate off it and found the filter blocked with crud , so i simply removed the filter and put the pump back in , i find it now idles higher by about 500 rpm and definatley has more power { found out on first test drive when doing a u turn in 2nd , gave it a bit and nearly did a 360 } , and it stopped blowing black smoke

so as far as the lift pump affecting the pump timing , on mine at least it does
 

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2.8 EFi GU found an extra cylinder after I fitted one.

When my mech pump 2.8s are brought into service they will have lift pumps.
 

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Discussion Starter · #9 ·
My thoughts: pressure supplied to the vane pump will not be the same as what comes out of the vane pump unless fuel can bypass the vanes. As the vanes only spin at the same speed as the injection pump, the pressure supplied to the injection pump will be the so close to the same , it would make very little difference if any.
The vane pump is PD, good point.
 

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Give it some goat
nissan
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well my car seemed a bit sluggish for the last couple of months and it was blowing black smoke at higher rpms where it never used to , i ended up pulling out the holley red lift pump that i fitted and pulled the base plate off it and found the filter blocked with crud , so i simply removed the filter and put the pump back in , i find it now idles higher by about 500 rpm and definatley has more power { found out on first test drive when doing a u turn in 2nd , gave it a bit and nearly did a 360 } , and it stopped blowing black smoke

so as far as the lift pump affecting the pump timing , on mine at least it does
Surely this wont be advancing the timing? I wouldnt think that on idle it would have increased the revs by 500 if you just advance the timing, if it did it would have to be set very retarded initially. It would have more likely been the restriction of the blocked filter causing the lack of power and the increase in idle. I presume you have adjusted the idle at some stage? I would be putting a replacement filter in there aswell, it is probably there to protect the lift pump. Is it your first filter in line?
 

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Learned the hard way - RD28t out TD42 in
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VE IP timing advance is indeed controlled hydraulically by the vane pump pressure. As to whether fitting a lift pump changes this I don't know, somebody needs to do some testing to confirm. Fact is, many fit a lift pump aftermarket to compensate for a worn IP and leaky fuel lines, and as an extra bonus, most likely get a bit of timing advance, which is always good for an bit more kick. Manufacturers who fit lift pumps will have the pump timing calibrated to suit I would think.
 

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VE IP timing advance is indeed controlled hydraulically by the vane pump pressure. As to whether fitting a lift pump changes this I don't know, somebody needs to do some testing to confirm. Fact is, many fit a lift pump aftermarket to compensate for a worn IP and leaky fuel lines, and as an extra bonus, most likely get a bit of timing advance, which is always good for an bit more kick. Manufacturers who fit lift pumps will have the pump timing calibrated to suit I would think.
Fair point.

I wonder if on a brand new injection pump if you would notice the difference.

All I can add is the fitting of the lift pump made a noticeable difference. Just off idle was better I noticed this mainly going up the steep part of my driveway after the lift pump it would idle up with no hint of stalling. General smoothness was improved and the engine revved much smoother and stronger from 3000 rpm onwards.

Cheers

Justin
 

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Give it some goat
nissan
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I still doubt that fitting a lift pump would advance the timing enough to really advance the engine, a small amount yes i can see but i cant see how it would change all that much. I think the increase in power comes from the increase in fuel being supplied to the lift pump. Where is oldmav or diesel tech when you them.
 

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No pics but I have a 100GPH carter through the floor just in front of the upper control arm crossmember on the drivers side. I drilled 3 holes thru the floor the same spacing as the carter bracket and put the grommets thru the holes in the floor.
Then just poked the posts of the carter pump through the grommets and put the nuts and washers on the inside.
It is a little bit noisy but I can't hear it over the motor because I dont have much of an exhaust on it. I reackon if you have carpet over the top it should be fine.

Underneath I have a section of inner tube bolted to the floor with penny washers at the front and it's cable tied to the crossmember at the back, so it covers the pump loosely like a hammock. This has been very effective at preventing gravel damage because it's loose and slows the rocks down. The front of my diff has no paint left on it at all from the gravel.
 

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SUI GENERIS UTE
GQ Ute 1990 Silvertop
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There is a number of posts/threads on this subject and pic's but i would suggesting a fitment as close to the fuel tank as possible is best for many reasons which have been pointed out before on here.

I still doubt that fitting a lift pump would advance the timing enough to really advance the engine, a small amount yes i can see but i cant see how it would change all that much. I think the increase in power comes from the increase in fuel being supplied to the lift pump. Where is oldmav or diesel tech when you them.
Lol 89 GQ old post can answer this, for electronic advance IP pumps have done no testing on them at all. but for the non electronic advance IP fitting a fuel pump like a holley red which works at 4 to 6 psi only helps the vane lift pump, at idle it does nothing to timimg but on old pumps it does help fuel supply hence a increase in idle speed. But what it does do is it advance timing a bit quicker as revs are increased hence the noticeable off idle response i cannot remember the exact revs the timing is all in by as i did this research stuff in 1990, but i do remember that the timing is all in about 150 to 200 rpm eariler. On older pumps the extra pump just brings the advance curve back to simulate a new IP. I have pointed out many times here the TD 42 likes a bit of extra timing depending on what you have done to the engine like 3 inch exhaust, the better the engine is aloud to breath the more responsive a bit of timing is to a point of course this is a bit trial and error people like Andy at Diesel tech would be able to tell you where the cut of point is. It is pretty easy to notice a too advance engine it stumbles at off idle response but this requires a lot of timing and would be way past the optimum timing point and would be increasing EGT on a turbo engine more than necessary. Like most engine tuning you need a bit of experience and knowledege to get best results. But fitting a fuel pump like a holley red is always a bonus for the TD42.
 

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"NOW TAKING BRIBES"
nissan
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Fitting my lift pump made a world of difference, no flat spots or bog downs anymore, these all happened after the new turbo and cooler was fitted, the pump fixed it all
 

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Weekend Warrior
Nissan patrol
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Probably not a bad idea for older injection pumps too.

My RD28ETi has a notable flat spot at 2600rpm.
 

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My lift pump some pics.

All the bits and pieces.


Brackets mounted in place, before powder coating.




This how the pre filter and pump sit inside the bracket.


In hindsight that style of pre filter was more trouble that what it's worth.

Cheers

Justin
 

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I was just about to ask you where you got the pre filter from... never mind then haha.
I'm looking for something with a coarse mesh strainer that costs less than the $200 aeroquip stuff and suits half inch lines.
I'm replacing the pickup in the tank with half inch shortly.

the filter I use now is a cheap and nasty plastic 3/8 filter on the standard pickup with a reducer to go to the half inch line on the pump.
 
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