Lack of power

[Dan01543]

So I have a 1996 volvo penta 5.0fl motor in my boat. I did a tune up and this is what I did.spark plugs and wires cap and rotor,ignition coil, new oil and oil filter,new fuel/water separator filter,new alternator and starter.all the electrical stuff was original from 1996.after the tune up I started it on the trailer and everything ran smoothly and ran great.i put it in the water today and it stalls when going into reverse and sometimes in forward. When I go to give it full throttle it goes about 20mph and runs very rough and back fires out the carburetor. But at 5 to 10 mph it's fine but it runs rough at that speed. In neutral I can throttle up the motor and it's running smoothly but when it's under load it has no power back fires out the carburetor and runs very rough. I had a half tank of fuel from the fall time and added fuel today. I did add fuel stabilizer to my tank.so I need help what is going on that I'm having this problems someone please help me.thank you

 

[dubs283]

After the tune up did you check/set timing and adjust the carburetor?

 

[Dan01543]

No I left everything the way it was I did a basic tune up.

 

[Dan01543]

I just have a cap and rotor that's it there's nothing to adjust with that

 

[dubs283]

I just have a cap and rotor that's it there's nothing to adjust with that

You also have spark plugs, wires, and fuel filters. And you must also check and set the initial timing after replacing any tune up parts

Since you are having runnabilty issues you should also inspect/adjust your carburetor and fuel supply system

 

[Dan01543]

But if it was a timing issue wouldn't it not idle.like it can be on the trailer and I put it in gear and everything is fine but when it's In the water and there's a load on the motor there's no power.its on the trailer and everything is fine.only when the motor is under load it acts up.i can put it in neutral and rev it and it's runs fine as well

 

[dubs283]

But if it was a timing issue wouldn't it not idle.

Engines that are severely out of time will still run, even if the firing order is incorrect they can at times still run with no load. Your speculation does not negate the fact that initial timing, proper timing advance and firing order must be correct in order for the engine to perform properly

 

[Dan01543]

So in the fall time before it got winterized it ran fine and this spring I did a basic tune up with new spark plug wires and plugs cpa and rotor and a new ignition coil. Other than that I didn't touch nothing that had to do with the timing. So is it possible with the new parts it threw the timing off a few degrees to make it run like this?I just don't get it im at the end of my ropes with this boat.and if it's still the timing could u please tell me how to fix it so I can try and get it right before I buy something I don't need please.

 

[dubs283]

is it possible with the new parts it threw the timing off a few degrees to make it run like this?......could u please tell me how to fix it so I can try and get it right

Yes, but off a few degrees may not hurt too much but if the timing was off before the tune up now it could be more off, follow? Also, did you ensure the firing order is correct before/during/after the plug, wire, cap and rotor replacement?

Best advice for you is to establish a known baseline. Ensure firing order is correct, may need an oem manual for this. I can tell you GM standard rotation engine is 1-8-4-3-6-5-7-2. It may be cast into the intake and correct if original. Unknown if you have a Ford based engine, could be a couple different firing orders there.

Get a timing light and oem manual, it will outline the timing procedure and let you know if you need a shunt tool for the module (electronic igniton only)

 

[Dan01543]

I'm positive the plug wires are correct because I switched 2 of them and it hardly run at all.i was told it could be a bad fuel pump because it's mechanically and it's 20 years old but I was told the back firing out the carburetor is a timing problem. Then I was thinking it's the carburetor is dirty because I did play with the mixture screws and the back firing did go away but it lost more power. So I only want to fix the problem and not have to to fix all 3 of them parts to find out that's not the problem.

 

[jimmbo]

Check the Firing Order, and verify that the Wires are going to correct Cylinder. Swapping a couple wires may or may not make a difference. However if you already have 2 swapped, 2 more can certainly kill the engine.

 

[tpenfield]

Running in neutral means nothing. (Lots of folks say their engines run great in neutral, and they are right)

As the others have said . . go through the wiring and timing to make sure something is not amiss.

(We) assume that it was running fine before the tune-up (?)

 

[Dan01543]

I don't know if it ran fine the mechanic that winterized the motor said it sounded good but that was at a idle.if it's not timing and the spark plug wires what else would it be that I could check for?