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gmendo's Avatar
 
Join Date: Jun 2011
Location: Rancho Cucamonga, CA
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No hot start, hesitation once started.

So I finally got my 930 back together. It did have 1/3 tank of bad (several years old), 1/3 tank of 91 octane (1 month old) and 1/3 tank of 100 octane (also month old) gas. It ran great at first but soon it developed a hot start issue. It starts fine when cold but it won't start when hot.

There is spark, timing is right, coax cable checks ok. Coil check ok, The fuel pumps do turn on. The sparks plugs look ok. But the only way to get it started when hot is by slightly pressing on the metering plate a few times while cranking.

When this issue first came up, once it finally started, it would idle rough for a few seconds, then it would run great. Then it started to hesitate under boost only. Now it hesitates almost all the time.

I'm stumped as to where to go from now. All this happened in the last two days. Is t possible that bad gas made good gas go bad, do I have gummed up valves in my fuel head? What do I check now?


Last edited by gmendo; 07-09-2011 at 09:29 PM..
Old 07-09-2011, 08:25 PM
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Also, at idle, the air/fuel ratio is solid at mid 14's. While hesitating at part throttle, a/f rapidly swings from 13's to 16's on the gauge. While on boost, it hasitates horribly and the a/f swings from 11's to 17's rapidly on the gauge.

Im starting to believe some injectors are not firing/clogged.

Where to go from here?
Old 07-09-2011, 09:28 PM
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You need to check your fuel pressures- typically poor hot start is leaking rest pressure - ie no residual pressure. But your other pressures may be out too. You may have a low total pressure.
Alan
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Old 07-10-2011, 03:07 AM
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I agree with Alan. You could possibly have a bad accumulator. Residual pressure value will confirm.
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Old 07-10-2011, 04:31 AM
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Where/how do you check pressure on a euro fuel head?
Old 07-10-2011, 08:54 AM
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Disregard the questing about testing fuel pressure. Fuel pressure has been tested.

CCP, CP and CP with valve closed are all within spec.

RP isnt good. It bleeds off too soon. I still suspect the injectors.

Any suggestions as to where to go from here?
Old 07-10-2011, 11:12 AM
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The injectors are closed when the engine is off and fuel cannot flow to them through the fuel head because you have no system pressure when the residual pressure (23psi after 10 min) is too low. The accumulator is the only place it can go. If your accumulator is original, it is either stuck or leaking or both. Invest in a new one and you will have eliminated most of your possible problems. Also, I would drain and refill the tank and replace the fuel filter. Good gas does not make bad gas good. You have moisture, alcohol by-products, settled dirt, and other bad things in the tank. The recirculating system we have will guarantee all of that gunk ends up in places you don't want it. Also dump some Sea Foam, BG44, Techron, or whatever you fancy in with the first tank, it will dissolve and flush out the nasties. It's less expensive than a rebuilt fuel head and almost as good.

Mark
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Old 07-10-2011, 11:42 AM
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Thanks Mark, It definately failed the RP test. So, if there's no possible way, fuel would leak through the injectors like a modern car, then I guess 'Im in the market for an accumulator. lol

Draining the tank and running seafoam sounds like a good idea. Now what to do with the old fuel? Hmmm

Also, injectors are out. Sure enough, 3 not spraying correctly. Now to clean them, flow them, and reinstall..

Last edited by gmendo; 07-10-2011 at 12:24 PM..
Old 07-10-2011, 12:18 PM
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I had the same problem would have a hard time starting when hot , when it would start it would idle rough and run rough it was the fuel accumulator, easy way to check is to disconnect the bottom fuel line of the fuel accumulator if there is fuel the that means that the diaphragm is broken , Replace that and your 930 will love you.

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Old 07-10-2011, 05:38 PM
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