How do I start merc 260 on stand?

[WILDMAN]

I've got those 3 1996 Merc 260 2.5 efi's that I bought on Ebay and I'm trying to start them on the engine stand. The fuel pump and starter is hooked up and they get spark, but no gas. If I sqirt gas in the horn, it fires right up, but the injectors don't feed it. The harness is'nt hooked up. What do I need to hook up so the injectors will fire? Thanx WILDMAN

[Raceman]

I stuck one of my old T4 powerheads (3.4 EFI) on a deckboat and it won't cold start without squirting gas in the throat. It will run fine once it gets going, so it's just a choke issue. I was told that the injectors always have power to the + side but fire by being provided a ground. It's unclear why my engine doesn't fire the injectors on the choke cycle as it should, but the advice was to provide a manual ground through a switch to the ground side of two of the injectors to fire them for cold start.

In your case, hooking up the harness will probably solve the problem.

[WILDMAN]

They're grounded through the starter, but maybe that does'nt ground the injectors. I know most motors start up with the harness unpluged, but all 3 of these do'nt, but will if I sqirt in gas. These motors do'nt have chokes.

[captcarb]

The injectors are powered all the time, so they need power to that circuit, the ecu grounds them to fire them. You need power to the ecu's for them to run.

BUT, whatever you do, make sure you have a kill circuit hooked up so you can shut them down.

I would suggest you hook up the electrical harness. Make sure the engine block is grounded also, you can kill the ecu's if they are not grounded.

Jim

[Rocket]

I just had the same problem on my 2.5 260 EFI with the injectors not feeding the motor, It was the outer switch box. Worth a try.:rolleyes:


PS. Wildman, Take off them props before ya start them motors! Ya can't push that hot foot very good without legs.


My two cents.

[Raceman]

Randy, they enrichen by firing the injectors when you hit the starter. As the Cap'n pointed out they ground through the starter circuit and have voltage to the hotside when the switch is on. So I guess it's technically true that they don't choke, but enrichen. I just always called any change to enrichen the mixture under startin' conditions chokin'.

[MIKE'S MIRAGE]

WILDMAN, FIND THE PURPLE WIRE FROM THE MAIN CANNON PLUG AND APPLY 12 VOLTS TO IT. THE ECM IS NOT POWERING UP. GOOD LUCK. MIKE

[WILDMAN]

Thanx Mike, I'll try that tommorrow.

[Raceman]

Randy, will the engines run after you get them started, or do they shut off when you quit squirting?

[WILDMAN]

they shut off immediately and do'nt even pop without a squirt, but they do fire right away. They all do the same thing, so Mike is probably right. I just hope the purple wire is the right one!

[MIKE'S MIRAGE]

don't worry, it is.

[WILDMAN]

Mike, I hooked up the purple, did'nt work. Hooked up the harness, the key turned it, but still no gas. Runs only if I squirt the gas to it. Two motors do the same. Whats up?

[MIKE'S MIRAGE]

DO YOU HEAR THE FUEL PUMP WORKING, IF SO, WHAT IS YOUR PRESSURE?

[H2Onut]

I had same thing happen on my 225 EFI, would spin all day long, no spit or spurt. It was the darn kill switch wires, had to tape them together !

Hope this is it, have a feeling...

[WILDMAN]

Pumps working, If it's the kill wires, would'nt it not fire with the gas I squirt in? Maybe I'll try another pump.

[H2Onut]

well, BL was over when I got the new motor, it spun like a raped ape, 2 times it spit, like fired for a nano second, thats what baffled me, but I put the yell/brw ?, wires together that go to control box and it lit right up. I hope them babies fire for ya, they look too cool.

[MIKE'S MIRAGE]

ANY WAY YOU CAN GET FUEL PRESSURE? RESON IS THAT I WANT TO MAKE SURE THE FUEL PUMP IS MOVING FLUID AND ALSO MAKE SURE WE HAVE A GOOD REGULATOR.

[captcarb]

Are both the fuel feed and return lines hooked up to something?

Jim

[WILDMAN]

Both fuel lines are hooked up and gas comes slowly out of the return. There must be decent pressure, cause I had a small leak that sqirted 10 ft. I'll try a different pump I guess.

[captcarb]

If fuel is coming out of the return line, you should have fuel pressure.

I assume the battery is hooked up like it would be in the boat since the starter works. Is the harness hooked up like it would be in the boat? Is the ECU connector plugged into the engine harness?

The ECU receives power from the red wire any time the battery is hooked up and the ecu is plugged in. It also receives power from the purple wire when the ignition switch is on. The injectors have power any time the battery is hooked up. The ecu needs to be grounded for it to work. Usually the ground goes from the block to the ecu mounting stud.

The start enrichment circuit is either actuated by pushing the key or from the starter solenoid, depending on how it is wired.

Look all of this stuff over and see if you find something.

Jim

[WILDMAN]

Well, I hate to post this, as it shows what a bonehead I am. I tried to start 4 of my 5 260's without any luck. I tried different harnesses, different fuel pumps, and ecu boxes, still no injector gas. Well, I got the 18 Liberator rigged and could'nt get it started, when a vetinarian friend of mine, who knows nothing about motors, asked if my fuel lines were hooked up backwards? DUH, guess what? We reversed them and hit the key, and WAHHHHH! How stupid am I? oh well, we may make it to silver glen for the party on Sat. yet! Thanx everyone for your help. Who would have guessed it was only a brainfade problem.

[captcarb]

I was wondering how you were doing, and I guess a few others were too. Glad you got them running.

Jim