Re: Top end revs on a 5.7 EFI / B1
 

Check for broken spark plugs too, sometimes the white porcelain part of the plug can break and cause an intermittant mis. Same goes for the distributer, take it off and check for arcing underneath. You can leave the wires on, just unfasten it and flip it over.

Re: Top end revs on a 5.7 EFI / B1
 

Well I just spent the last couple of hours tracing the HT leads and unfortunately the firing order was correct :(

Strange thing is though the instructions for identifying #1 on the distributor cap (previous in this thread) state that for normal small block chevy #1 is at the 6:30 position and EFI 5:30, mine's starting at 4:30?!?

Tried both 5:30 & 6:30 and she won't even fire up, starts immediately on the old sequence.

Anyone got any ideas??

Steve.

Re: Top end revs on a 5.7 EFI / B1
 

Well, does it run smooth and start good? Chances are that the firing is ok. When I bought mine, it started rough and was 10 mph slow but it was a new boat for me so I wasn't really sure what to look for. If you went and switched that plug wires on me now, I could tell you in a nano-second after firing it up that something was wrong.

My point is, you will notice change more with your boat the more you get used to it, I did anyway. So has something changed since the last time it ran good?

To check the firing order from scratch, there is a way to do that. The problem with the 4:30 and 5:30 position is that it's all kinda relative. The distributer is moved around to adjust timing, so those 4:30 and 5:30 positions are kinda general marks to shoot for.

To find the number one, there are a couple ways to do it. The way I use is this. Find the #1 cylinder according to the diagram, take out the spark plug, gently wad up a small part of a paper towel to plug the hole and bump start the motor until the pressure shoots the wad of paper out. (don't push it in to far, so it gets sucked down on the intake stroke) When the paper flies out, that will leave the piston at top dead center (TDC). Now trace that plug wire to the distributer and check that the rotor (under the cap) is pointed at the right plug terminal. That make sense? Then trace the others from there.

This is a kinda gorilla way to check it, it if you have nothing else to go from.

did you check all the plugs? Did you check under the cap to look for arcing?

I'll go look at mine and take some pics. Mine is carbed though, not sure what yours is.

Re: Top end revs on a 5.7 EFI / B1
 

This is my motor, firing order printed on the front of the intake. 1994 Carbed 350 MAG. 250 HP


http://i47.photobucket.com/albums/f1...5/IMG_0747.jpg



This is looking from front to back (not perfectly straight back, slightly to the left.) you can see #5 and #7 wires off. If you count 2 wires to the left of that, you can see #1, they are printed on the cap on mine. So according to this, the 4:30-5:30 position is if you were to look at this from the back of the boat or engine. From this front view, #1 on mine is really about the 11:30 position.
http://i47.photobucket.com/albums/f1...5/IMG_0748.jpg

This is just a shot of the #1

http://i47.photobucket.com/albums/f1...5/IMG_0752.jpg

Re: Top end revs on a 5.7 EFI / B1
 

She's actually running OK, just missing that top end and a bit jittery under 1000 rpm.

I just re-read your first post. This sounds exactly what mine did with a firing order problem, I would recommend re-checking the firing order again.

If it's not spark problem, I would next look towards fuel or fuel injection. Old fuel from sitting all winter can cause problems too.