Engine won't start

[Dono]

Hi All,
1971 Spit rebuild. All together but won't start and would appreciate ideas.
1. Fuel pump okay, fuel getting into carb.
2. Carb rebuilt prof by Joe Curto/NY, so s/b okay.
3. Electronic ign w/ new coil; strong spark shows at plug when removed and grounded.
4. Timing is correct, not out by 180 deg. Valve & pistons checked visually for proper position relative to the rotor position.
5. Cyl compression on each is 148-150 lbs. Is this too high?

I'm stumped. Thanks, Dono

 

[DNK]

If you got good spark at the cy. and you say the timing is close enough it's gotta be that no volatile liquids are getting to the spark

 

[hondo402000]

you could spray starting fluid in the carbs and if it fires then its a fuel delivery issue

 

[Andrew Mace]

I had a similar situation years ago with a Spitfire 1500. I finally decided to turn on the ignition, loosen the distributor and then turn it back and forth as I worked the starter solenoid button...until it caught and fired up! Not terribly scientific, but it worked for me.

I'm curious, though: After a lot of cranking and no firing, do you find that the plugs are wet with fuel?

 

[Dono]

Hondo, Andy,
Thanks for the ideas. I tried the carb fluid, engine 'burps' then quits. Carb float bowl is full. I'll try Andy's suggestion of loosening the carb and tripping the starter solenoid and see if I can get it to fire up.
I also wonder if the float bowl is letting gas into the intake jet/needle, since the plugs remain dry after cranking.

More to come, Don

 

[tdskip]

Well if you have spark and fuel then should be timing.

 

[DNK]

Tom, maybe the volatile liquid ain't getting past the carbs. He says the plugs are dry.

 

[Rhodyspit75]

I know you said the timing wasn't out 180 degrees. Mine wasn't either and I had all the same problems. I had checked it and had a friend review it and we were 100% sure. Friend went home, I went in and had a beer. Found another article on timing printed that one, went back to the garage and lo and behold. I had been wrong ( I was on the wrong stroke) and the engine was running in 5 minutes.

 

[TR4]

If the plugs are dry after cranking, I would ask if the carb needle and jet were preset. Are they adjusted completely closed? Normally, they come back bench tested and set to install but there is a chance they were closed for return shipping.

 

[DrEntropy]

If Joe did 'em they were bench set.

Mebbe put a vacuum gauge on it first. Be somewhat informed as to whether or not you have an intake leak...

I'd be for putting a timing light on it. If the #1 plug is firing on (or near) the 8° mark, pull the wires from the cap and put 'em in 180° from where they are now. Whadd'll it hurt? Get a BIG backfire and a: "THAT didn't help much!" if its wrong. :shrug:

"95% of all carb problems are in the ignition." etc.

 

[Dono]

Engine won't start - Success !!

Greetings Brit-heads!
Success! Thanks to all for their valued ideas. So what was it? The timing,....no - well a bit since I have to yet put a timing light on it, it idles rough. The spark,...no. Unlike the old Sat movie serials, I'll not make you wait. It was the fuel. The carb was prof rebuilt by Joe Curto. Though fuel was getting into the carb, it was not leaving the float bowl. Inside the float bowl, the floats push up on a pin that shuts fuel into the carb. When low, the floats drop the pin, allowing fuel in. At the top of that pin assembly is a tiny mesh screen cap. It was barely passing air & no fuel. I pulled that off, reassembled it all, put starter fluid into the intake and after a couple turns it caught and continued to run - thus getting fuel thru to the needle. So add this as a possible cause of fuel starvation situations. I have to 2 in-line fuel filters, so I'm leaving that mesh cap off.
Have a great Sat and Father's Day! Dono

 

[poolboy]

Re: Engine won't start - Success !!

So you found that something had the screen blocked so fuel could not enter the float chamber or was the screen interfering with the needle valve's plunger, keeping it from dropping with the float ?

 

[Deleted member 8987]

Re: Engine won't start - Success !!

You take spray carb cleaner, clean the screens, and re-install, or whatever garbage is coming in from your fuel line will rapidly make the carbs in need of another going through.

 

[Dono]

Re: Engine won't start - Success !!

Howdy Poolboy,
I'd say the screen plugged fuel flow, it does not move, only a pin inside the part. Dono

 

[Dono]

Re: Engine won't start - Success !!

Hi TOC,
I did clean it and may reinstall, but I wanted to prove the fuel stoppage idea first. Thanks, Don