Perkins Starting Issues - Help !

[atraitees]

Hey folks,
I have a 3 cylinder Perkins diesel and in order to start it now, I have to prime the injectors... In other words, before I start it, I have to loosen the nut in the fuel line by the injectors and pump the little finger pump until fuel squirts out. Once I get it started she runs forever. No issues at all. But, if I turn it off for more than 5 mins I have to do the whole series over again to get it started. It seems to be "sucking" the fuel back out of the injectors. I have cleaned out the vent but still get this issue. Any clues??

[S/V_Surya]

You have a air leak in your fuel line somewhere. Check filters first, nice an tight. I dont think you would see a fuel line leak because not enough pressure. Once they are opened I hear they air tough to seal up. Check all fittings. When did this start happening? I have a 4107 and changed filters last year and have similar problem.

[atraitees]

Actually, it started happening right after we did a complete tune up including changing the filters... I will double check those. Thx.

[atraitees]

Ok, I checked all the lines. I do not see any way that air can get in. All the clamps are nice and tight and doubled. The filter is nice and tight and I see NO fuel anywhere while running...

(sorry for the double post...) :-P

[chiropaul]

Possibility of your fuel pump being defective and allowing back flow in the lines. I would check that.

[Chief Engineer]

Air leak in lines, possible a pinhole leak in the fuel pickup, when you changed the filters....did you change ALL the gaskets.....does your return go back tot he tank or recirculate to the secondary filter?

[Pblais]

Air leaks really are a PITA to find. Evey clamp and any valves can start leaking just a bit of air even an older boat that never leaked before can get them (I have had them too). When it's been sitting a while is the perfect time for an air bubble to get in there.

I would rule out the fuel pump itself since you eventually get the engine running well. Connections any place a hose goes could be the spot. They can get dried out and a little bit hard. Not enough to see visually. Check hose clamps as they loosen with vibration over the years. Checking close to the filters might be a good start then go forward. Not getting the filter seated would do it too. This is just a little bitty one it would seem.

[skipmac]

I had a really PITA leak in my fuel system that I just could not find. Finally got a gallon jug of clean diesel and started disconnecting the fuel system at different points and feeding fuel from a hose stuck in the jug at each point.

Worked my way backwards through the system until I reached a point where the problem appeared so had isolated the leak between the last two test points. I ended up with a new Racor water sep.

By the way, thanks to Chief Engineer and a few others on the forum that helped me track down the leak.

[atraitees]

Arrrrgh!! What a PITbutt..... I suppose I'm going to have to take it piece by piece. Is there any way to "purge" the system to look for fuel leaks under pressure. I mean other than running the engine??... lol Btw.. My return goes back to the tank.

[Pblais]

Is there any way to "purge" the system to look for fuel leaks under pressure.

The fuel system is a low pressure system. Testing under high pressure would be a problem and expose a lot of problems while making many worse. Air leaks are a PITA.

I found mine and it was the drain for water on the bottom side of a plastic Racor designed for spin on filters. The little drain was leaking air. Finding it was really a lot of work. Fixing it was cheap. Such is the way of many boat problems. If you knew exactly what it was every time it would be easy to own a boat.

Why do boat yards charge so much? It's because they have to find the problem if they expect to really fix it. Why some fail to fix the problems is because they never found the real one even if they did find one. You can have more than one air leak too.

[atraitees]

Unfortunately I have to wait until I get to better weather to get that deep into the engine. We are currently in Punta Gorda, FL. We are heading south in another few days. Then I can get away from the ICW and concentrate on it. Tomorrow I have to fix a main halyard. While getting the dinghy off the boat my loop came out. I forgot to stitch it. lol No biggie, that's why I carry the sampson kit... lol Thanks for all the support. Give me a few days and I will let everyone know what it was.

[Chief Engineer]

As my Port Engineer (He's in his late 80's now) said to me.

Chief....what were you doing to the main BEFOE it stopped running?

He said that with a smile on his face BTW.

[atraitees]

I was able to solve the issue. When we put the new fuel line on we did not use tape on the brass fittings. To make life easier, I put a primer ball on the line. SO much better than that stupid little thumb pump!!

[SkiprJohn]

Well done!!!
Isn't it a great thing to be able to keep that engine running when you need it.
regards,

[grimshaw]

Perkins 4108 fuel injection pump - starting problem

Last year I did a lot of work on my engine, and after had trouble starting it. I spent hours looking for air in the low pressure side. The engine would after a while (10 seconds) start when cold but when hot refused to start, without bleeding. Once running it ran and idled well. No significant smoke of any color. Turn the engine off after an hour, and immediately attempt to restart failed.

I spent the whole winter fiddling with the system, and eventually after losing the engine 20 miles from home, did what I should have done and took the fuel injection pump off. It was leaking fuel from the main front seal. (the leak was not visible because the leaking fuel went into the timing gear housing at the front of the engine. Another sympton that I should have picked up was that when bleeding and cracking open the injector line at the injectors and turning the engine it took a long time for fuel to squirt out.

I sent it in for testing. It required new seals and a new head. Interestingly when tested the fuel pressure was low on the injection side, but the cylinders were not damaged- just worn - after 25 years, so that when the fuel and pump heated up the clearances were not tight enough to create the necessary pressure to the injectors. The replaced head solved the problem, and the pump tested out at 100%.

It was not easy to find a good company to do the work, however I found on the internet a company called Oregon Fuel Injection in Eugene. They sell (if in stock) rebuilt 4108 pumps with one year warrantry for $680. Because my pump needed a new head the cost was just over $1,000. The turn round after receiving the pump was two days.

The folks there are very helpful. Telephone # 1-800-452-5055, ask for Mark.

website: Oregon Fuel Injection, diesel fuel injection pump, turbo, injector and diesel performance product specialist.

By the way it is not easy to take off the pump. On the inside next to the engine is a bolt that needs a 7/16 allan key, and a very narrow space to get at it. I bought a key ($1.75 - about 3 inches long) and cut the elbow piece off and fitted the longer part to a 3/16 inch socket (epoxied) for a 1/4 inch drive extension. You can use a 3/8 drive, but the space is very tight and a 1/4 inch is better.

Hope this post helps anyone who runs into similar problems. Moral of the story is that the low pressure side is not always the problem!

Dick Grimshaw