Found the problem. The fuel pressure is dropping to 30psi when I hit the gas pedal. I have to go through the 30+ year old fuel system and get it up to par. One option is to run a low pressure pump by the tank to feed the high pressure pump relocated by the motor.
OK, I haven't posted here in a while. Turn out the problem with this motor was a big lack of fuel pressure. The gas had a back flow check valve on it which needed a pretty good pull from a mechanical pump to draw fuel. The Walbro just couldn't keel up and I think I killed it. Put a new pump on it and removed the valve and it runs good now. Had it on the water all weekend, but it still needs a good tune on it. I'll get it on the water this weekend for a nice long haul run and make a new log.
OK, Thanks to all that helped, but this was all for not. The trouble the entire time was fueling issues. The first Walbro inline pump just never worked at all. The second one worked for a week or so then died. Now I installed a Silverado tank with a new in tank pump and it works GREAT!! So time to tune.
I finally got the laptop plugged up to it last night and the first thing that stood out was the timing wouldn't go above 15*. In the jet boat world everyone always uses mechanical advance only. These engine have HUGE cams and spin very freely so getting any vacuum is a problem. I'm not sure how these motor measure the cylinder charge info, but setting up an RPM based table WOKE THIS MOTOR UP!!! Did the first run at 28* max'd out at 3,200 rpm, then a second run with 30* at 3,200. Both runs showed zero KR. At WOT, which is where jet boats spend 90% of their life, the O2's are pegged. In the end the boat picked up about 450 rpm on the big end and pulled hard out of the hole.
First scan is the stock timing table.
Scan A is with 28* rpm based timing.
Scan B is with 30* rpm based timing.
Was thinking if trying 32* and bringing it in quicker keeping a close eye on KR.
Here's the tune and the config file for the runs above. Note the spark timing in tune 3 and the straight change in tune 4. Is my big cam throwing off the MAP, which in turn is not calculating the correct advance?
That's a hell of a timing table. I'll try it out this week. Gonna lake test again at Lavon on Wednesday night. Hey Sam, you're one town over from me. I'm in Rowlett. I'll have this boat at the Harbor Concert on Thursday night. Come out to the docks and say hi if you're there. I'll have the engine cover open to show off the EFI Vortec motor in a 70's jet boat.
That table's not going to hurt anything, is it? That's a lot of timing. Up to 49 in some values there. How about the VE table? It's running way fat at WOT, but I was messing with the table when I was having fueling issues. I was going to go back to a stock table and add 5% across the board, jet boats like to be a little fat on fuel.
Last edited by blazeracer; 06-19-2012 at 12:21 AM.
That table is perfectly fine for a jet boat. Only run 93 octane fuel in it. The problem you are going to have is the engine coolant temp due to the engine running off of the water in the lake. You are only showing 110-125 degrees of temp where as a normal car will see a constant 190-210. Its hard to burn all of that fuel with a very low coolant temp. The timing in that table I provided will solve alot of the issues.
I made the mistake of going down to the Harbor during on of those concerts last year. I am not brave enough to try that again. Being on the dock is one thing. Having to drive out of there in a crewcab 2500 truck with that traffic is a nightmare!
I have a boat I planned on tuning Sunday at LRH but I may end up at Eagle Mountain insted.
Well, I lost about 200 rpm on that timing table over the straight up 30* table. Water temp may be an issue. I made a 32* table and had some KR with that. We have a big event coming up in Broken Bow in a couple of weeks so I'll probably run with the 30* table for the time being. The motor's happy and make as good of power as the 460 Ford that came out of it.
May try to go with a closed cooling system this winter.