89 4.3 Mercruiser Low RPM at WOT

[Gary H NC]

Re: 89 4.3 Mercruiser Low RPM at WOT

You should have a clear plastic tube running from the fuel pump up to the carb.Usually if the diaphram goes bad you will see fuel in that tube.It has that for safety measures incase of fuel pump failure.
I say go for it on the carb rebuild,not that hard at all.8)

 

[180shabah]

Re: 89 4.3 Mercruiser Low RPM at WOT

Carb rebuild is not that difficult, just take your time and remember - they key word is CLEAN.

 

[tbeaze24]

Re: 89 4.3 Mercruiser Low RPM at WOT

I know clean is the most important thing. Like I said, I worked in a parts store for almost 20 yrs. I never rebuilt one, but you here all kinds of things from the mechanics you sale to. Most would say just take it apart and let it soak in carb cleaner for a few days before you ever start the rebuild. Thing is, after going out yesterday, and playing with the throttle, I know the engine is good, and has the power, it is just starving for fuel. I didn't know about the anti siphon valve, and my glove compartment was broke and I had to tear it all down, and the whole console on the left side of the boat was apart, and I looked down and saw where the fuel line went into the tank. At least I know how to take it all apart to get to the outlet of the tank. I am going to take that back apart, and drain the tank, and clean out as much of that as I can. After that, I am going to take it back out again, if no difference, I am going to rebuild the carb, and probably go ahead and replace the fuel pump, hell I have replaced everything else, so why not go ahead and do the fuel pump, at least then, I will know what it isn't. thanks again, and keep coming with the tips and info.. Just happy to have a boat again, although this is my first inboard,,,,,,Will keep the board posted, Tim

 

[tbeaze24]

Re: 89 4.3 Mercruiser Low RPM at WOT

Gary, I did see that tube, not sure if it is filled with fuel, but it is definately wet inside. Will keep everyone posted,,,,tim

 

[Gary H NC]

Re: 89 4.3 Mercruiser Low RPM at WOT

It should be dry.Unless some condensation built up in it but thats doubtful....It very well may be a sign the pump is going bad.
If you can get to the end of it where it connects to the pump,pull it off and see if fuel runs out.
You know how auto fuel and water pumps have that weep hole? same principle as that but it sends it to the carb to burn instead of running into the bilge.
8)

 

[tbeaze24]

Re: 89 4.3 Mercruiser Low RPM at WOT

I knew about the weep hole, and absolutely understand about wanting to send it back to the carb..I just got my Clymer manual today, and after reading it over and over, it really seems like everything is pointing to the anti siphon valve.... Anyone have any idea where the anti siphon valve would be on a 1989 190ES Caravelle with a 4.3 V6??? I am going to go try to find it, but any help would be greatly appreciated. Thanks, Tim

 

[180shabah]

Re: 89 4.3 Mercruiser Low RPM at WOT

Follow the fuel line from the pump back to the tank. the brass 90deg fitting that is screwed into the tank is the anti-siphon valve.

 

[Reel Poor]

Re: 89 4.3 Mercruiser Low RPM at WOT

The fitting screws into the top of your fuel tank. The hose to your fuel pump is attachet to it.

Should look similar to this one below. Internal in the fitting is a spring and check ball

 

[tbeaze24]

Re: 89 4.3 Mercruiser Low RPM at WOT

Thanks Guys, From what all had been told to me here, I was pretty sure it was at the tank, but after reading my Clymer manual today, it never really mentioned the one at the tank, just that it had one. But I will tear apart my left side console to get back to it,,,,,and I am highly suspecting the accelerator pump, after reading a lot about it, the boat did sit for almost 2 years. At this point, I am pretty much just gonna go ahead and rebuild the card, replace the anti/siphon valve, and the fuel pump and be done with all of it. Wish me happy motoring in the near future?????8) Thanks again, Tim

 

[Gary H NC]

Re: 89 4.3 Mercruiser Low RPM at WOT

Let us know how it all turns out Tim. You may not have to replace the anti-siphon valve.just clean it and make sure it opens and closes.I got a feeling cleaning out the old fuel and some carb rebuilding,check out the fuel pump good and you will have it made..Good Luck!

 

[Don S]

Re: 89 4.3 Mercruiser Low RPM at WOT

While it may be the antisiphon valve is slightly plugged, it could also be the screen on the pickup in the tank (That keeps the antisiphon valve clean) that is plugged up.
If you go up to the post by real poor and read the link he posted on testing the boats fuel system, you will save yourself a LOT of parts changing and hit and miss checking of the wrong parts by just doing a few simple tests with a gauge.
With the gauge setup and a test run, it shouldn't take more than 30 minutes to locate the EXACT problem.
Shoot, it could be nothing more than a loose clamp on a hose.

 

[180shabah]

Re: 89 4.3 Mercruiser Low RPM at WOT

Happy motoring in the near future8)

 

[tbeaze24]

Re: 89 4.3 Mercruiser Low RPM at WOT

Well Guys, Here is the update, I rebuilt the carb, and to my surprise,,,,,it actually started right back up. Have not taken it back out, but it did seem to idle better, and the couple of times I rev'd it up, it seem to respond a lot better. After I got inside it, I could not beleive it was getting any fuel at all. It was very dirty, and the float was saturated. Then I decided I probably better go ahead and replace the water pump impeller. OMG, it was almost gone and the pickup tube was broken off and in the bottom of the foot. I got the impeller put back in,,and yes I did replace all the seals and housing. Will put it back on tomorrow and take it out as soon as I can, thanks for all the help, and wish me luck. Thanks again, Tim

 

[Gary H NC]

Re: 89 4.3 Mercruiser Low RPM at WOT

Glad to hear you got it back together ok.
Good thing you checked the impeller.You definatly don't need an overheating problem.
Let us know how it runs on the water!8)