Motor does not run with the engine cover on.

[TIGGER]

I got my boat running a couple week ago and put the engine cover on before I went to the lake this past weekend. The engine would not run with the cover on. It was not getting enough air. I had to put some 4x4's between and bungie the cover down to give the engine enough air to idle. It did not look pretty but it got me thru the weekend. What is the trick in getting this thing to run with the cover on?

[SmokinLowriderSS]

I've got no trouble in my Taylor. mine inhales through the bilge vents as well as down the sides of the interior all the way from the front seats. Where are and how large are the air passages through/arround your cover to your engine?

[kp216]

My CobraJet breathes the same way as Smokin's Taylor does. You might want to check for anything blocking your air flow, such as life jackets, towels, equipment.
I will say this though... It does not run as good with the doghouse on, especially as the temperature goes up and the motor starts breathing all that hot air in there.
If I pull the doghouse and put my K&N flame arrestor on, I gain just a hair under 200 rpm on the top end.

[Hallett19]

put a scoop on :cool:

[TIGGER]

My engine cover / dog house has a built in scoop with about a 2" x 5" opening. Unfortunately I can't post a picture of my cover on this system, :idea: One bilge vent is open. The other has a fan that remove the fumes, etc from the bilge. The engine is able to draw from the back as well as behind the seats but it is still not enough air? Having the bilge / exhaust fan on makes no difference. Also taking off the air cleaner does not help. The carb (Edelbrock) is brand new with only a couple three hours of use on it.

[SmokinLowriderSS]

There is something cutting off your airflow somewhere. The scoop is borderline smaller than the carb throats but you need more airflow. I'd just have to start scouring over the boat. If yours has an interior that leaves an opening betwen it and the hull (like mine) the engine will inhale through there. Check there for a blockage from a life jacket or some such item. The admiral & I actually keep our jackets in this area next to the front bucket seats without problem but between that and the louvered vents on the rear sides of my deck, we have plenty of airflow. The engine will suck backwards past the bilge fan as well as long as it is not running. My louvered vents face opposite ways to scour the bilge automatically while running on plane also. The left set faces fwd, the right set faces aft (and has the fan). We've run a 454 easily at 5,300 rpm as is no troubles, and that takes a LOT of air.

[cokesbody]

i had the same problem that you are haveing when i first built my engine with the little 6 or 8 inch marine breather on it, so i just cut a hole in my cover and put a scoop on it .

[TIGGER]

I am still having trouble with it. I do not want to modify the cover as it is original to the boat. There is nothing behind the seats blocking air flow. Can I add another blower to the other side? One to blow air in and the other to remove the fumes from the bilge?
I also have a little bit of an exhaust leak. I need to double the header gaskets. Could that be part of my problem?

[xs ultra]

exhaust leaks not good . it's hot enough under the hatch with no exhaust .
Had the same problem with my boat.I added a fiberglass scoop on it.Runs better. more rpm and speed.

[kp216]

I am still having trouble with it. I do not want to modify the cover as it is original to the boat. There is nothing behind the seats blocking air flow. Can I add another blower to the other side? One to blow air in and the other to remove the fumes from the bilge?
I also have a little bit of an exhaust leak. I need to double the header gaskets. Could that be part of my problem?
I know the feeling about not wanting to modify the original cover. I'm going to make another top for mine to put a scoop on.
Adding another bilge blower fan will not help. They don't move enough air, plus, they're designed to remove fumes from the low part of your bilge. Your hot air problem is up top.
The exhaust leak is hurting you as well. It's putting even hotter, contaminated air in there.

[SummerObsession]

OK, I know this is probably way off base, but it happened to me in my race car once.
Car ran fine on the stands in the pits, warmed up, head for staging. Put nose on car, etc. Go to fire up the car, car won't start. Missed the time trial and headed back to the pits. It turned out the sheet metal around the removale front end (magnesium) of the car was touching both the positive and negative posts on the coil, grounding it out and not allowing fire.
Trimmed up the sheet metal a bit and won the first three rounds!
Long story, but could it be something like this is happening? Have you changed any electrical or other compnents? Food for thought.

[flat broke]

I am still having trouble with it. I do not want to modify the cover as it is original to the boat. There is nothing behind the seats blocking air flow. Can I add another blower to the other side? One to blow air in and the other to remove the fumes from the bilge?
I also have a little bit of an exhaust leak. I need to double the header gaskets. Could that be part of my problem?
Okay, so you have poor airflow to begin with, then you are displacing what little fresh air you have in your bilge with exhaust gas, making it even harder for the engine to get suitable air flow. Fix the exhaust leak first and fore most. If the motor doesn't run properly at that point, I say to at least try a second bilge blower to introduce air into the engine compartment. Yes the little bilge blower isn't big enough to soley provide enough air for the motor to run on, but it might be just enough to get you over the threshold you need to run properly. Since the blower is only $20, it's not the end of the world if it doesn't work.
Chris

[Oldsquirt]

......I had to put some 4x4's between and bungie the cover down to give the engine enough air to idle. .......
Considering how little air is needed to idle, I doubt that it is an airflow problem. Even the one vent should provide an adequate supply of air. Heck it should idle with your hand over the top of the carb with just a little space between your fingers letting air in.
Are you absolutely, positively, 100% sure that the cover is not physically interfering with something?
An exhaust leak in a closed engine compartment will give you at least three problems. First, and most important, is it can create an EXPLOSIVE situation. Second is the additional heat. Third is the fact that it acts like an EGR valve on a car, but it will never shut off. Will hurt perfomance. Fix that leak! Doubling the gaskets is the Mickey Mouse solution. Check the manifolds for warpage. Resurface them if needed. If both surfaces are truly flat, only a film of high-temp silicone should be needed.

[Wally_Gator]

OK, I know this is probably way off base, but it happened to me in my race car once.
Car ran fine on the stands in the pits, warmed up, head for staging. Put nose on car, etc. Go to fire up the car, car won't start. Missed the time trial and headed back to the pits. It turned out the sheet metal around the removale front end (magnesium) of the car was touching both the positive and negative posts on the coil, grounding it out and not allowing fire.
Trimmed up the sheet metal a bit and won the first three rounds!
Long story, but could it be something like this is happening? Have you changed any electrical or other compnents? Food for thought.
First thought for me... Could the cover be pinching fuel line, touching and electrical? Any interference at all?

[SummerObsession]

Any luck?

[909]

First and most important is to fix the exhaust leak. I guarantee that you do that and it'll run. Probably would run better with a scoop on it but I promise you that the exhaust is killing it. Air/fuel mixture burns, fuel/carbon monoxide will not burn. It needs to have an oxidizer. I had an exhaust hose pop off the transom tip and it killed the engine quick, would not restart. As soon as I opened the engine cover it would fire. I'm sure what seems like a tiny exhaust leak is probably bigger than you think. Gaskets are cheap, get a set and let us know how that 1 change does.

[TIGGER]

I thought I would post an update.... I doubled the gaskets last weekend and took the boat out on Monday night. My problem seems to be solved. The boat ran fine with the cover on. Now I just need to fix the tough steering.... but that is for another post..... Thanks guys!