strange knocking noise above 2,000 rpm (5.0 efi 95')

[bruceb58]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

You have to do it under load. In the driveway, you don't have the same flow as under load.

 

[perna00]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

ok, thanks for the info! I'll let you know what I discover.

 

[perna00]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

Well, I hooked up a gas can with a 4' 3/8" hose to it. No change in pumps. Even in the driveway the low pressure pump got hot and the high pressure whined very loudly. No change from the two different supply lines. I already replaced the low pressure pump. I'm going to assume the high pressure pump is as bad as the rest of the old boat parts and replace it as well. Autozone sells one (yes it is marine use) for around $100. Hope this is my issue.

On a side note, I removed the low pressure supply line from my gas can and it still ran for about 3 minutes without the low pressure hose having any suction on it (put my finger on it to test), does that just mean the VST was full or possibly a different issue?

 

[perna00]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

I might have found the problem!!!!!

I turned the key to "on" for a second after removing the pump and all other kinds of debris came out of the VST. Would this just be from the lines and what the pump screen stopped or does the VST possibly need replaced?

 

[Don S]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

You don't have to replace the VST, just take it apart and clean it out and put on new seals and gaskets. Also flush the lines to the pump, re-check the low pressure pump.
Then take the filter housing the low pressure pump mounts to off and make sure there is no paint inside. Seems the fuels these days eats the paint.

I didn't miss to far about what the problem was in your other post did I.

 

[perna00]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

Don, good call on the debris call in my other thread! The new pump started whining after I installed it so I took it back off and found new debris in the new pump. I took the cap off the vst and sure enough there was quite a bit of debris in the bottom. I removed the pump and pressure blew the vst and the lines coming/going into it. They are clear. I checked my water/fuel separater and there was some black debris in it as well. Maybe the tank is collecting debris? What do you think? Also, when I had the lines off of the vst, I ran the low pressure pump and filled the vst up about half way to check the fuel quality. There wasn't any paint or debris in it. Should I still remove the low pressure pump again? I appreciate the help. I actually might get this solved in time for some spring fishing!

 

[Don S]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

Sounds like you need to clean the tank and start replacing filters more often and checking them to make sure they are clean before you damage more pumps.

 

[perna00]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

That's the strange part. I bought the boat after it sat for a few seasons. I drained the tank completely (without much sediment), put on a new filter, ran it less than 6 times, and changed the pumps. I have under 10 hours on the boat. The last owner must have been pretty rough on it.

 

[Don S]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

Might want to look at the fuel line between the tank and the engine. It may be deteriorating inside and that is what's in your pumps.

 

[perna00]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

Sounds like a plan to me. I'll do that today while I'm waiting for my gasket for the vst to get here. Do you think I might need to remove the injectors to clean them also?

 

[Don S]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

I would bet they do. You also need to flush all the fuel rails and hoses so the injectors only see clean fuel. Your whole fuel system is probably contaminated.

 

[RogersJetboat454]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

IMHO with all the trash you are finding in the fuel system, I would be putting some thought into having the injectors cleaned/rebuilt after you get all the junk out.

 

[perna00]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

Will do. I'll have to line up all the new gaskets I'll need for the intake manifold, fuel rails, and connections. Can I use automotive gaskets/o-rings on them?

 

[perna00]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

I got the injectors off and cleaned all the screens on them. I can't find anyone around town town to bench test them and clean the internals. Is there a way I can clean them efficiently myself?

 

[perna00]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

I read up on the details and I'm just going to go to a shop to get them to bench test/clean them. After this, the entire fuel system (except FPR) will be new/functional. Hopefully this will fix my problem once and for all!

 

[perna00]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

Well, I was too impatient to wait, so I hooked up my own injector cleaner. I did some research and made my own kit out of a can of carb cleaner, a hypodermic needle, and a simple push botton wire setup. They were spraying badly at first but after a few forward & reverse cleanings, the spray patterns are perfect now. Tomorrow I should get all my needed gaskets and be able to test the boat out on the water again. Here is a link for the home made injector kit that I took the idea from. This wasn't me, but it was informative. http://www.youtube.com/watch?v=7aT4S1lIBAY

 

[Don S]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

I did very similar to that a few years ago. Problem is, it doesn't clean the injectors. They have very fine filters in the injectors and when you back flush them, the crap ends up still in the injector. May take a week or so, but they usually plug back up and start misfiring again.

 

[perna00]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

Man, that's not what I was hoping to hear. I first blew air into the top screen (not sealed, just enough to blow out the debris from the top opening), then I back flushed them, then forward flushed them. Do you still think I'll have problems?

 

[Don S]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

Try it and find out. I already gave you my opinion of the DIY method. Ir's your time during the summer.

 

[perna00]

Re: strange knocking noise above 2,000 rpm (5.0 efi 95')

Thank you, I appreciate your opinion. If it does run right for a little while then repeats, at least I know exactly what needs done and what was the problem I've been seaching for during the last 6 months. I always look at the glass half full; I believe it in but my wife always disagrees and says it is a bad practice.