lost pressure in priming pump

[80cruiserfan]

I have been experiencing a sudden engine shut down, usually after a strong acceleration (climbing a steep hill for instance). When this occurs, the engine starts to weaken, as if running out of gas, until it shuts off. A friend told me it might be the priming pump that is defective and losing pressure. In fact, this morning at home, I revved the engine a few times, and right before it shut off, i pumped the priming a few times, and it started to idle normally again.
Any opinion?

 

[roscoFJ73]

I have been experiencing a sudden engine shut down, usually after a strong acceleration (climbing a steep hill for instance). When this occurs, the engine starts to weaken, as if running out of gas, until it shuts off. A friend told me it might be the priming pump that is defective and losing pressure. In fact, this morning at home, I revved the engine a few times, and right before it shut off, i pumped the priming a few times, and it started to idle normally again.
Any opinion?

This is not the priming pump causing this. Its just there to pump fuel when there is air in the lines.
What you have done is probably exposed a problem with low pressure in the injection pump.

I have a newly adjusted and rebuilt pump and pumping the primer makes no difference to mine.
Other's reckon they can speed the engine up at idle by pumping

There is a fuel pressure regulator valve that diverts excess fuel back to the fuel tank that can be adjusted and will increase the pressure inside the fuel pump.
According to the manual you need to have a gauge connected to monitor the prssure during adjustment.
See pages FU76/77 in the FSM

Or your feed pump inside the injection pump maybe wearing out which means a strip down.

You could also try turning the idle up if it is slow

Some fit inline fuel pumps to fix this ,but I prefer to fix the problem


EDIT I see yours is probably a 1HD FTE. Im reading from an older manual so it may not be exactly the same.

 

[2 Bees]

First I would drain the fuel/water separator. 2nd check the primary fuel filter screen & banjo fitting for any obstructions. 3rd change the secondary fuel filter. 4th check for air leaks. 5th replace lift pump primer. 6th rebuild lift pump. 7th check and or drop fuel tank for any obstructions in tank (like fuel additive cap seal).

 

[Tapage]

First I would drain the fuel/water separator. 2nd check the primary fuel filter screen & banjo fitting for any obstructions. 3rd change the secondary fuel filter. 4th check for air leaks. 5th replace lift pump primer. 6th rebuild lift pump. 7th check and or drop fuel tank for any obstructions in tank (like fuel additive cap seal).

X2 in the secuence .. but I would place the air in the line due to some pin hole or the primer itself .. a test that you can do it's addind a electric fuel pump to pressure fuen on the filter and make a test ..

this give you an idea if it's the sucction function fo the IP or air in the line ..

IMOP the 1HD-FT are not that sensitive to the air on the line as same as older models ..

 

[roscoFJ73]

If he had leaks in the fuel lines or primer pump big enough to starve the fuel pump,there would be massive amounts of diesel leaking out.
He would also find it very difficult to start ,but there is no mention of hard starting

 

[80cruiserfan]

Let me try to better illustrate this:
2 weeks ago I took the car on a weekend trip. Roughly 500 km round-trip, driving at an average of 110km/h. The problem did not occur once, so it did not feel as if I have a problem in injection system or fuel supply.
On the contrary, while driving in town, it happens randomly after climbing a hill, as I said earlier. (lots of hills where I live)
The other times I see it happening is if I rev the engine a couple times , while in my driveway.
No matter how it happened the symptoms are the same: idle speed slows down dramatically, and the only thing that will prevent an engine shut off is either priming the pump, or revving the engine gently a few times with the accelerator.

the engine is indeed the 1HD-FT. Mileage is about 104,000km.

Thanks!

 

[roscoFJ73]

Let me try to better illustrate this:
2 weeks ago I took the car on a weekend trip. Roughly 500 km round-trip, driving at an average of 110km/h. The problem did not occur once, so it did not feel as if I have a problem in injection system or fuel supply.


Thanks!

There is not much else it could be unless there is an electrical problem connected to the fuel system.
What have you checked ?

 

[Tapage]

Other option are if you are driving on hi speed means hi rev range .. the air in the line ( due a bad IP plunger ) it's less evident ..

 

[80cruiserfan]

My mechanic is pretty confident it is a priming pump failure. Gonna get it at the dealership today. I will keep you all posted.

 

[panoramic]

I also strongly agree with that sequence.

I recently solved a similar issue on my 12HT. The engine would run rough or die after pulling off highways, going up long hills or stopping at a quick red light. I had added small inline fuel filters during my initial build. The first filter was almost completely blocked with paint chips and rust after 4000 miles. The result was that there was some suction in the fuel line and it was pulling air into the system. I never saw fuel leak out - but I could see air filling up in a filter just before the lift pump when the engine ran rough or died.

If I drove slowly or stop the engine briefly the air-pocket would dissipate enough that the engine ran fine again until pulling hard again.

- Eric

 

[80cruiserfan]

I can't find the part locally.

I wanted to ask: who knows a reputable JDM parts importer in the US?

 

[intoyotawetrust]

Hey 80cruiserfan,
Did you ever resolve this issue??? What did it end up being? I’ve got an exact issue with my 1hdfte...

 

[eric888]

In the past few weeks, I also facing this issues of my 1HD-FT. I'm waiting for the primer now. :/

 

[bryce0225]

I have a question regarding the primer: once pumped and primed, should the primer remain stiff indefinitely or will it lose stiffness after a few moments?

 

[roscoFJ73]

It will go soft within a minute or so. I imagine what happens is the pressure from the hand pump opens the fuel bypass valve on the injection pump and the fuel goes back to the tank.
These fuel systems are low pressure until the fuel gets into the distributor head.

 

[bryce0225]

update for my truck:
The racor prefilter was the issue. It seems like the the inlet and / or outlet was letting air in and pressure out. I am currently running an all new OEM filter and primer pump system and it’s working flawlessly.

 

[Squash]

You are not the first person to experience that issue.
Have seen nearly brand new Mercedes filters leak so bad that we used our feet to prime!
Something two mechanic's and a laptop couldn't figure out.