"Prime" the fuel system before starting?

[Brian VT]

This may be nitpicking, and it's really no big deal, but I'm curious.
When starting from sitting overnight or even a week it never starts on the 1st try. But it always starts on the 2nd try.
My normal would be to hold the glow plugs on for 6-8 seconds. Pedal to the floor. Crank for 3-5 seconds. The sputtering tells me it's not gonna start.
Glow again for 5 seconds. Starts right up.
So...what I've been doing now from cold is no glow, pedal to the floor, crank for 3-5 seconds. Obviously no start. But I believe I am "priming" the fuel system. Then I glow for 6-8 seconds and hit the starter. Bang. Starts right up. I figure why waste glow for the 1st try if it's not gonna start anyway.

So...is my thinking that I'm "priming" something correct? Is this normal or am I having slight leakdown when sitting and that's why I need to "prime" it? Or is there maybe something else going on here?

 

[IDIBOBS]

Hey looks like you have been having this issue since November 2023. From that thread you say you plug you heater in at 29deg. You really shouldn’t need a block heater at that temp. At my place it gets into the mid teens at night and many days won’t get above mid 20s and I’ve never used my block heater, it doesn’t actually work.

This new thread above sounds pretty common if it works for you then yes that’s basically what you’re doing, getting fuel to the injectors. In reality yea you have a leak down (air intrusion) of some sort. A motor that is all working perfectly won’t have this issue. You would turn the key, push the throttle 1/2 way and release for over 32deg f, or all the way down and release for below 32deg f, (this sets the high idle) wait for glow plug light to go out and start the motor.

But how many people have the time and or money to have everything working like factory? Some yes, many don’t. I have replaced all the fuel lines both fuel in and return and all the fuel line fittings ect. Mine can sit about 2 weeks in The cold and still start up on first try. After 2 weeks i do what you do, give it a few cranks then wait for the light to go out.

 

[Clb]

Fwiw
I seem to recall that the start sequence was/is/could be, key on depress throttle to set hi idle plunger return to idle, hit key and go....

Mine is a barn queen, it sits for months on end plugged into a tender.
I start it as above.
It usually fires on the first few revolutions and idles flat like.
This floor it to start is new to me.
However long I've been here, not heard it till recently.
I think drainback is happening.
Good luck
Cb

 

[Brian VT]

Yeah. I figured a little drain back or something like that. Thanks.
It doesn't matter if it's 0 deg. or 95 deg. and it doesn't matter if it sits for a day or a week. It always seems to need a couple seconds of cranking to "prime" it before the actual attempt at starting. Then it starts almost instantly. Once it starts then it's good for the whole day. I think it's been like that since I got it 4? years ago. I've since replaced the injectors, pump, and return lines (not because of this "issue").
Again, it's really no big deal. I don't even consider it a "problem" and I'm certainly not going to try to find the source (for fear of screwing something else up).
I was just curious if I was "diagnosing" it correctly.

 

[FrozenMerc]

Does it do it if you don't touch the pedal during cranking, ala modern EFI gasoline automobile?

 

[IDIBRONCO]

This floor it to start is new to me.
However long I've been here, not heard it till recently.

I usually do that in the winter time and let off as the engine starts. That's also following the factory instructions that are on the sticker placed on the driver's side sun visor. They say to depress the throttle pedal half way for above 32* and fully below 32* while cranking the starter. Does anyone really do this in the summer? I don't except to set the fast idle.

 

[The_Josh_Bear]

Yeah. I figured a little drain back or something like that. Thanks.
It doesn't matter if it's 0 deg. or 95 deg. and it doesn't matter if it sits for a day or a week. It always seems to need a couple seconds of cranking to "prime" it before the actual attempt at starting. Then it starts almost instantly. Once it starts then it's good for the whole day. I think it's been like that since I got it 4? years ago. I've since replaced the injectors, pump, and return lines (not because of this "issue").
Again, it's really no big deal. I don't even consider it a "problem" and I'm certainly not going to try to find the source (for fear of screwing something else up).
I was just curious if I was "diagnosing" it correctly.

I'd lean more towards injector leak down than air intrusion. I also think that if all you're doing is giving it 3-5 seconds crank first then every time you do that it saves a GP cycle, warms up the starter, gets the oil flowing, primes the IP/injectors...I got no issue with it. Probably a good thing overall. I should try it myself!
Does it spin faster the second crank? Could maybe be a weak starter/cable setup that does better when warmed up, just guessing.
Definitely not guessing on the injectors priming though, that's a thing. Ideally these should hold firm for a month but many do not and leak down overnight.

 

[ihc1470]

Josh an interesting theory. Do you think the pressure just drops to zero or do you also believe the line drains between pump and injector?

My owners manual has this to say about starting. Temp above 32 f depress accelerator pedal 1/2 way and hold. Temp below 32 f depress accelerator fully and hold. Warm engine start with pedal at idle position.

 

[Brian VT]

I'd lean more towards injector leak down than air intrusion. I also think that if all you're doing is giving it 3-5 seconds crank first then every time you do that it saves a GP cycle, warms up the starter, gets the oil flowing, primes the IP/injectors...I got no issue with it. Probably a good thing overall. I should try it myself!
Does it spin faster the second crank? Could maybe be a weak starter/cable setup that does better when warmed up, just guessing.
Definitely not guessing on the injectors priming though, that's a thing. Ideally these should hold firm for a month but many do not and leak down overnight.

I put a Powermaster starter in last year. It is fantastic. I don't think it turns slower when cold but maybe?
Injector leak down sounds plausible. I'd consider sending them back to Russ for testing but, sadly, he is no longer with us.
Could an overnight tranny fluid treatment help with that or would it need a rebuild?

 

[Clb]

I'd not thought of leak down, does it smoke different @startup?
This one is new to me so I have to deffer to others.

 

[Kdo58]

5-8 seconds is not long enough, when iwent to a push button glow plugs, I took a glow plug out and hooked it up to 12 volts and I counted to 14 before it got glowing red. I also have a electric fuel pump.

 

[IDIBRONCO]

Could an overnight tranny fluid treatment help with that

It could possibly help. At worse, it won't hurt anything.

 

[Brian VT]

5-8 seconds is not long enough, when iwent to a push button glow plugs, I took a glow plug out and hooked it up to 12 volts and I counted to 14 before it got glowing red. I also have a electric fuel pump.

6-8 seconds of glow seems to work fine on mine. I've held it longer and it doesn't seem to make any difference.

 

[clakelaw]

There is a fix for this, I just did it to my 92 E350. First, make sure all the glowplugs are good. If so, I let mine stay on until I see the battery gauge shows no more extra voltage drop. This way I know they are fully hot.

The fix is to remove and plug the shrader valve on the fuel filter housing and also remove and plug the fuel return line on the housing. Those last injector returns on each bank are then both tied together and a "T" is installed in the middle for the injector pump return to tie in. Doing this removes alot of problems and potential leak issues. The second part to this is to install a check valve on the fuel tank side of the fuel pump. This prevents the fuel from siphoning back into the tank. Fuel will always be there at the pump regardless of how long the vehicle sits. I bought this entire mod as a kit from Classic Diesel Designs in TX. It was pretty easy to install. Its sold as an upgraded return line kit. Its made a difference for me.

 

[Black dawg]

My truck has done the same thing for as long as I can remember. Almost never even acts like it will start first try, starts second try like you forgot ro turn something on the first try. Must have a small leak somewhere, as it is much worse if parked uphill at all.