4108 slow to start or what did I do wrong?

[sloopdavidb]

I have a rebuilt 4108 with 100 hours on it I changed out all of my filters last week. Before I would hit the starter with the throttle on idle and it would start immediately. Now I have to set the throttle about half open and crank for ten seconds. Runs fine after it starts. Any thoughts on what might be the on reason for the change.
Thanks David.

[noelex 77]

Sounds like you are getting some air in the fuel system.
Most likely from the primary fuel filter when it was changed. What type is it ? Some models can be a bit difficult to seal well.

[sloopdavidb]

Thanks Noelex,
I have the racor duel 500 system, I'm pretty sure I'm good there. I think your right about air getting in some where (wanted to hear some one else say it). I'll go through the steps again to bleed it and see what happens.
Thanks.

[SkiprJohn]

Aloha David,
There is one screw on the fuel injection pump that should never be touched. It looks a bit like a bleed screw. Just be careful about that one. I've had to bleed a 4-107 several times before I got it just right. Great engine. It'll last forever.
If you want help let me know.
John

[noelex 77]

Originally Posted by sloopdavidb

Thanks Noelex,
I have the racor duel 500 system, I'm pretty sure I'm good there. I think your right about air getting in some where (wanted to hear some one else say it). I'll go through the steps again to bleed it and see what happens.
Thanks.

Yes I think the Racor 500 series is the best and usually seals well. If you have a dual system you can easily eliminate the primary fuel system. There are still lots of places for leaks.
I have got an air leak in my system somewhere and still have not found it.
If your problem persists see the post on Yanmar starting .Other forum members have provided some great, although so far unsuccessful, guidence which you may also find useful.

[Jesse]

All the Perkins 4107 & 4108 engines that I'm familiar with were equipped with air purging devices. Once you get the engine started it returns the trapped air to the fuel tank and requires no further fiddling. They differed slightly from engine to engine but were always part of the fuel filtering system. Check closely, yours may be similarly equipped. if so the air is probably entering the injector pump through a loose connection or leaking seal. If there is any evidence of a tiny fuel leak on the i/p that would be a likely source.
Jesse

[Boracay]

My late Ford had a Perkins lift pump. I found out why there was a collection of old ones in the spare parts bin...

Problems with the lift pump would give symptoms similar to those you describe.

If it was not replaced as part of the overhaul I would buy a new one.

They are not expensive nor are they hard to fit. Just make sure the lever sits properly on the cam and the bolts/nuts/washers don't fall into the bilge.

If the fuel lines/clamps are old I'd be tempted to replace them as well.

[sloopdavidb]

So I went through the fuel system and tightened every thing that was not already tight. Started the same but I expected that, next time hopefully she'll fire right up. If not I'll look into the lift pump.
Thanks for the help. David.

[Chief Engineer]

There is a bleed screw on the side of the injection pump.

I had a similar problem on a customers boat.

Hooked up a portable tank to engine.

Voila' problem was in fuel line to tank.

[SkiprJohn]

Hey David,
Please let us know how she starts the next time you go out.
JohnL

[richardhula]

Spent a lot of time solving a similar problem on my boats Volvo TMD31B. It has a Separ 500 filter. Almost identical to Racor, uses same filter element, bowl etc. BUT the small sealing ring under the cover is different. Took a long time to find but that was the problem. The Racor one supplied with replacement filter seated too loose in the locating groove under the T bar. Fitting a larger one that sat proud of the groove cured the problem.

[sloopdavidb]

Well I went through every fitting in the fuel system and it is starting quicker but still not as fast as before I changed the filters. If I set my throttle about half open she comes to life after just a few seconds, start kind of sluggish and then I have to throttle back as the RPM starts to climb. I think I'll look into getting a new lift pump as I can't tell if it was replaced when they rebuilt her. I do not think we have any one on the Big Island that stocks Perkins. John do you know any one in Kona maybe? I guess I'll let my fingers do the walking on Monday.
Thanks again for the help guys. David.
Oh, yes I did change the secondery filter and gaskits again.

[Boracay]

If you take your old lift pump to a place that sells parts for trucks they may be able to match it.

Please don't blame me if this does not work.

[slacker]

Could be a silly question but here goes:
Is the starter spinning the engine fast enough? The reason I ask is that when we got our first boat with a diesel insted of a gas engine we had starting problems. I was sure it had something to do with the fuel system. After a lot of fusteration spent replacing filters and repeated bleedings I gave up and called a friend with a similar engine. He came over a gave it a quick listen and said "your engine is not turning over fast enough" I cleaned all the connections but nothing changed. Finally I pulled the starter motor and upon removing the end plate I discovered 2 of the 4 brushes were so worn down that they barely made contact and the other two had frayed wire strands. After replacing them and reinstaling the starter the engine fired off instantly. Havent had aproblem since.

Mike

[sloopdavidb]

Thanks Mike'
Funny you should mention that. I did just swap to my reconditioned spare starter ( I did not want to wait till I really needed it to find out if it worked). I wonder. I suppose the only way to find out would be to swap back, DARN. I think I'll let it ride for awhile. I do trust the the shop that rebuilt the starter but the houseing is a little different. Maybe it is cranking a little slower, I can't tell by listening. David.