97 Challenger Bogging at 5K

[Lifted5.4Lariat]

Hey my names Brent.

Been having some tough luck with my 97 challenger..

First off I had a clogged oil filter which ended in a top end rebuild.
Then I had really bad cavitation which was the carbon seal.
Now i'm having a bad bog around 5k and it will never go to WOT strait off the line and it always bogs at 5k.

The symptoms are that it will just stop revving up at 5k. If I bring the throttle back down to 4500 and punch it SOMETIMES it will go up to WOT at 7k, but sometimes there is zero difference and it will stop right back at 5. If I have a 400+ pounds it will ussually take 2-3 mins to get it above 5k and if its just me maybe 30 seconds. Sometimes when i'm toying it it seems like I have to work it up. For instance, after bogging at 5k and dropping down to 4500 then punch it it will climb to 5500 then hit a bog and drop back down to 5k then I drop the throttle down to 4500 and punch it to 6k. This will sometimes work and sometimes it will act like it is going to climb all the way to 7k but then it hits a bog and drops to 5k.

Rave valves have been cleaned twice since the rebuild and I have noticed some oil under the cap and even under the piston of one. I cannot see any visible damage to it, but it is an original as the other rave setup looks new compared to this one. Could this oil be the cause of my problems?

I will note that I am on my third tank of 87 octane fuel since the rebuild. With my first tank I ran it with 2.5 ounces per gallon in the fuel on top of the injection and I dont believe there is much if any oil still in the fuel. However, when the engine bogs there is a significant amount of smoke coming out the exhaust, but when I look at the plugs they dont look oily at all, at least compared to the ones out of the first tank of fuel. Oil injection tank doesnt seem to be going down much either per tank of fuel, an inch max. Why would it be smoking so much? Once I get it to WOT by messing with the throttle it seems to smoke a normal amount.

The previous owner said he had the shop rebuild the carbs, all fuel lines are new and black, and the engine bay looks extremely clean. It was a very well taken care of boat and this problem has me stumped.

What do you think it is/ suggest I do?

I really would like to get the boat running well before the heat of summer gets here!

Thanks, Brent :willy_nilly:

 

[Lifted5.4Lariat]

I'll also add that changing the plugs seems to make a difference somewhat. Just makes it easier to get out of the bog, but it ussually comes back after around 5 mins of driving..

I hope its something simple...

 

[Lifted5.4Lariat]

Once I thought about the smoking I realized that when it is bogged at 5k the throttle is really at wot even though the engine is at 5k. That would mean the oil pump is wide open putting in full oil even though the engine isn't at wot.. Still doesn't explain why it's so hard to get revved up.

Also it idles at 1500 in water and 2300 out of water. Does that sound normal?

 

[CaptSteve]

I had the exact same problem when I rebuilt my carbs. I changed everything I could think of, rave valves, plugs, tightened all connections, etc. Finally I brought it to a mechanic.

What my mechanic found on mine was that the pulse hose going from the engine to the carb had a leak and was sucking air. This hose is used to pump the fuel into the carb. He replaced the hose and readjusted the carbs and now it runs like a scaled pig.

Don't know if this is your problem, but you might want to check the hoses going to the carb.

 

[parrothd]

Hey my names Brent.

Been having some tough luck with my 97 challenger..

First off I had a clogged oil filter which ended in a top end rebuild.
Then I had really bad cavitation which was the carbon seal.
Now i'm having a bad bog around 5k and it will never go to WOT strait off the line and it always bogs at 5k.

The symptoms are that it will just stop revving up at 5k. If I bring the throttle back down to 4500 and punch it SOMETIMES it will go up to WOT at 7k, but sometimes there is zero difference and it will stop right back at 5. If I have a 400+ pounds it will ussually take 2-3 mins to get it above 5k and if its just me maybe 30 seconds. Sometimes when i'm toying it it seems like I have to work it up. For instance, after bogging at 5k and dropping down to 4500 then punch it it will climb to 5500 then hit a bog and drop back down to 5k then I drop the throttle down to 4500 and punch it to 6k. This will sometimes work and sometimes it will act like it is going to climb all the way to 7k but then it hits a bog and drops to 5k.

Rave valves have been cleaned twice since the rebuild and I have noticed some oil under the cap and even under the piston of one. I cannot see any visible damage to it, but it is an original as the other rave setup looks new compared to this one. Could this oil be the cause of my problems?

I will note that I am on my third tank of 87 octane fuel since the rebuild. With my first tank I ran it with 2.5 ounces per gallon in the fuel on top of the injection and I dont believe there is much if any oil still in the fuel. However, when the engine bogs there is a significant amount of smoke coming out the exhaust, but when I look at the plugs they dont look oily at all, at least compared to the ones out of the first tank of fuel. Oil injection tank doesnt seem to be going down much either per tank of fuel, an inch max. Why would it be smoking so much? Once I get it to WOT by messing with the throttle it seems to smoke a normal amount.

The previous owner said he had the shop rebuild the carbs, all fuel lines are new and black, and the engine bay looks extremely clean. It was a very well taken care of boat and this problem has me stumped.

What do you think it is/ suggest I do?

I really would like to get the boat running well before the heat of summer gets here!

Thanks, Brent :willy_nilly:

You need to make sure you have the "newer" slotted rave valves and are using the springs with red on them...There was a service bulletin, to replace the raves and update the jetting on your boat, you may want to check it out, you can search the forum for details.

You have extra smoke from adding the premix, this could also be clogging the raves which can cause the 5k hangup, you should re-clean the raves valves and the slots, then see what happens without adding the premix...I'd also make sure the lows speed screws at 1.5 turns out and the high speed are closed on the carbs and verify the oil injection cables is connected and adjusted properly..

 

[Lifted5.4Lariat]

The raves are as you described and an authorized seadoo rebuilt the carbs last summer for the previos owner. What I discovered is the screws on the raves were all the way screwed in and from my reading that may cause them to bog out like my 787 is. Is it possible to adjust the screws with the air box on? Would bli be better off setting the high speed to 1/8 to stay safe?

 

[parrothd]

Unscrew the red caps on the rave valves, see what works, leave the carb with the stock settings.

 

[Lifted5.4Lariat]

Well unscrewing the red caps to flush fixed 99% of my problems. It used to take me 10 trys to get it above 5k now once in every 10 accellerations it still has the bog. Really happy for now, but not giving up. Surely there is something else.. Just happy I can now enjoy the boat.

If it is so important to check the color of the plugs doing that 15 min wot test why is it so ritual to set the high speed jets at closed?

 

[Lifted5.4Lariat]

Is this aligned correctly?

 

[parrothd]

looks good..