TheSamba.com :: View topic - m-TDI (Landy pump) lift pump needed?

Sun Jul 21, 2013 9:33 pm

The ECU can compensate easily for a 6psi difference in internal pressure. The internal pressure is always much higher than 3psi. It's more like 40-150psi. The ECU also controls timing by limiting pressure to the advance piston. The timing requested can't be achieved when internal pressure is too low, not too high.

Sun Jul 21, 2013 9:38 pm

Agreed, I'm just saying that 43gpH is still enough to turn you're whole car to a pool of molten metal, that's like a full tank in what 20min?

I think there results were due to increased timing and duration and mostly applies to modifi :) ed engines. But if it works for you then it works.

Sun Jul 21, 2013 9:50 pm

kgold708 wrote: Agreed, I'm just saying that 43gpH is still enough to turn you're whole car to a pool of molten metal, that's like a full tank in what 20min?

The need for the high volume is not due to the amount of fuel squirted out of the injectors, it is due to the amount of fuel that is sent back to the tank, I mentioned this in an earlier post of mine in this thread, but maybe you missed it.

kgold708 wrote:
I think there results were due to increased timing and duration and mostly applies to modifi :) ed engines. But if it works for you then it works.

The general consensus on TDIclub was that it helped low end power and start up, I know TDIclub has its ups and downs, but that was the consensus.

Have you daily driven an E-tdi to be thoroughly familiar with how it operates and then added a lift pump to it to see if there is any difference? I suspect you haven't and are talking about this topic from a purely theoretical viewpoint, which has its merits, but there are a lot of things that should "theoretically" be true in this world that are not.

Sun Jul 21, 2013 10:10 pm

All the factory VWs with lift pumps also have fuel coolers on the bottom of the car, keep that in mind as well. Perhaps the lift pump adds more heat to the fuel?

I though I was having an issue similar to this maybe, I installed a Mk3 TDI one way fuel valve near my fuel filter (nearly the highest point). I was concerned fuel was siphoning back into the tank after stopping the engine. Mine is ECU controlled though. Occasionally I have a slightly longer cranking time but I'm not concerned with it.

One thing the lift pump is good for is refilling the fuel filter after changing as well as priming the pump.

Mon Jul 22, 2013 1:55 am

The Land Rover's were equipped with lift pumps and VW added it later on. It can't hurt to add one. That's at least my thought. I called the a-bit-more-fancy-parts-shop and ordered one, will have it this afternoon. 2.5 times the money, but they sell good stuff.

The thing is, the engine always starts instantly in all conditions except when I've been doing a bunch of stop and start procedures in a short period of time. If it's cold outside I will not even notice a problem. Verrrry annoying.

Mon Jul 22, 2013 8:04 am

hans j wrote: All the factory VWs with lift pumps also have fuel coolers on the bottom of the car, keep that in mind as well.

The ALH automatic trans cars do not have a lift pump (neither do the maunal trans cars), but they do have a fuel cooler, the auto trans cars came with an 11mm injection pump instead of a 10mm pump like the manual trans cars, the 11mm pump heats the fuel more than the 10mm pump, or so the story goes.

The 2004 PD injected VWs were the first TDIs to be built with a lift pump, that fuel system cannot suck fuel from the tank, unlike the older rotary pumped TDIs.

Mon Jul 22, 2013 8:05 am

Have you daily driven an E-tdi to be thoroughly familiar with how it operates and then added a lift pump to it to see if there is any difference? I suspect you haven't and are talking about this topic from a purely theoretical viewpoint, which has its merits, but there are a lot of things that should "theoretically" be true in this world that are not.[/quote]

No, I haven't daily driven a E-tdi.

The OP seems to be running a 1z with a landrover inj. pump. I believe the landy's had a mechanicle diaphram lift pump mounted to the block. He also lives on an island in sweden, I think all of our input in this thread is theoretical mostly. I've also never driven a 4cyl diesel landrover.

Couldn't he just need to replace his fuel filter "theoretically" ?

Mon Jul 22, 2013 9:22 am

kgold708 wrote: I think all of our input in this thread is theoretical mostly.

With regards to the topic of this thread it is all theoretical, and we are somewhat off topic with the lift pump/bosch rotary pump discussion, but it is related to the topic and provides more than no information for Sven. I have provided information from real world experiences, from my self and many others on TDIclub, this seems to offend you, why I don't know.

Mon Jul 22, 2013 9:34 am

jackbombay wrote: kgold708 wrote: I think all of our input in this thread is theoretical mostly.

With regards to the topic of this thread it is all theoretical, and we are somewhat off topic with the lift pump/bosch rotary pump discussion, but it is related to the topic and provides more than no information for Sven. I have provided information from real world experiences, from my self and many others on TDIclub, this seems to offend you, why I don't know.

I'm not offended in the least, I'm sure adding a lift pump will solve the problem.

There may have been other solutions, there's a lot of unasked questions in this thread.

Mon Jul 22, 2013 9:34 am

What type of return bolt do you have on the pump,the number is engraved on it:55 or 75?

Mon Jul 22, 2013 9:46 am

kgold708 wrote:
I'm not offended in the least, I'm sure adding a lift pump will solve the problem.

Ok, you're not offended, but you're being obtuse and sarcastic, neither of which is helpful.

Mon Jul 22, 2013 9:48 am

To the original poster. Do you have a clear line on the inlet to your pump? If you feel you need a supply/lift pump to resolve your hard start hot problem, I would expect to see some air bubbles in the inlet line when it won't start. The rover may have had a pump because the tank was not a gravity feed setup like the vanagon is.

I think you have something else going on. Adding a 12 volt power directly to the fuel cutoff would be a good place to start. This would eliminate the vans wiring and ignition switch. I don't know how long this condtion presists, but I'd also be inclined to crack the injector lines and see if fuel is being delievered to the injectors when it is hot.

Our ALH TDI "E" was having an intermittent hard start hot, but ended up being a combination of the factory map in the ECU and a battery that was on it's way out. Since you have an "M" pump much of the information on the TDI club as it relates to "hard start hot" would not apply.

Mon Jul 22, 2013 9:52 am

jackbombay wrote: hans j wrote: All the factory VWs with lift pumps also have fuel coolers on the bottom of the car, keep that in mind as well.

The 2004 PD injected VWs were the first TDIs to be built with a lift pump, that fuel system cannot suck fuel from the tank, unlike the older rotary pumped TDIs.

FYI - The tandem pump on the PD engines will suck fuel from the tank. I drove my '04 PD Wagon for two years with a dead lift pump before I replaced it.

Mon Jul 22, 2013 10:42 am

Good to know, when the PDs were new I read up on them a bit, but as I don't own one I don't read much about them very often.

Mon Jul 22, 2013 12:27 pm

Yyyada yada yada, you guys are just mumbo jumboing between each other! Stop read forum's like your opponents are angry. They aren't but you think so because you read an argument instead of listen to it. Classical psychology and you get stuck in the trap over and over again. :)

My filter is new. My feed hose is a clear hose and no bubbles. The Shut off valve is already relay fed. Does the valve click? Yes. Does it work? Hard to tell...
I'm rewiring some cables and I will check the connector to the solenoid, maybe I have another valve I can switch to, I'll dig in the shelves tonight.

ALIKA T3 wrote: What type of return bolt do you have on the pump,the number is engraved on it:55 or 75?

Was that to me?

rsxsr wrote: To the original poster. Do you have a clear line on the inlet to your pump? If you feel you need a supply/lift pump to resolve your hard start hot problem, I would expect to see some air bubbles in the inlet line when it won't start. The rover may have had a pump because the tank was not a gravity feed setup like the vanagon is.

I think you have something else going on. Adding a 12 volt power directly to the fuel cutoff would be a good place to start. This would eliminate the vans wiring and ignition switch. I don't know how long this condtion presists, but I'd also be inclined to crack the injector lines and see if fuel is being delievered to the injectors when it is hot.

Our ALH TDI "E" was having an intermittent hard start hot, but ended up being a combination of the factory map in the ECU and a battery that was on it's way out. Since you have an "M" pump much of the information on the TDI club as it relates to "hard start hot" would not apply.

As written, I have no bubbles and the valve is already rewired. The thing is, there's no chance what so ever to crack the lines before it will start. I had an idea that maybe my timing was too advanced, but that isn't clearly the problem as it starts in a blink of an eye when it starts. I have a starvation and it only happens when it's really hot. Must figure out where the heck this comes from though...

And yes, I live on an island. :)

Mon Jul 22, 2013 12:52 pm

Diesel fuel boils at a pretty high temp. Higher than I think the pump would get as a result of heat soak after shutting down hot. So that is probably not it. When the engine has sat over night at ambient it starts fine, so unless the glow plugs are the difference, the pump is not losing prime sitting overnight. So heat would make the pump peices expand. Could it be worn pump internals? Seems that would affect running more than starting though.

Years ago, I came across a few 4 cylinder and 5 cylinder diesels that were worn out. They would start fine cold, but when they got hot, they would crank and crank and not start. Unplugging the glowplug temp switch so the glow plugs would always work during cranking, and they would start just as good as they did cold. That was not a true fix, but cheaper than an overhaul. Add the supply pump and report back. I know it is frustrating, such a simple basic design and yet causing you a headache.

Mon Jul 22, 2013 12:52 pm

Well my theory is that your fuel is superheating in the pump after shutoff to perhaps 200 degf . This hot fuel is either leaking back out of the pump or its lower viscosity maybe bypassing internally or its lower density is causing low fuel quantity.

Have you tried giving it some pedal before/while cranking the first time when hot?

Mon Jul 22, 2013 1:32 pm

I was thinking of hot fuel too, but the weird thing is that it starts after a while. Maybe the cranking causes new fuel in? I did try some pedal but didn't feel much of a difference.
i'm just passing by the computer, had to get some soldering stuff from in house. Back to work now!

Mon Jul 22, 2013 1:33 pm

kgold, you may be discounting the fact that others, including myself, have used the LR pump on the VW TDI engines without issue. My van with the LR pump starts instantly regardless of ambient temp. Adding a clear section to the return off the pump would show air exiting the pump and might give a good clue.

Mon Jul 22, 2013 1:59 pm

I noticed that my ALH has one of those fuel coolers. I'm not familiar with these. Are they necessary?