New motor - lost fuel pressure January 03, 2008, 04:26:42 AM We were testing out the new engine in the car and haven't had any problem getting it started most of the time today, with exception of a few times the starting sing when the engine goes to fire. A few hours ago, right after getting the driveshaft put on, we went to start the car and it started, died, and wouldn't start again. We now have no fuel pressure.We had a leaking fuel injector which we pulled out, re-oringed, and reinstalled and the leak has gone away but we still have no fuel pressure. Trying to reset the fuel cutoff switch does nothing (it doesn't click, it feels like its not engaged at all). Any ideas on where to start? On key in we get the priming noise of the pump so its fine but we haven't had a chance to pull the fuel filter yet.Help!btw, the car sounds completely different than the 222,000 mile SO it replaced - basically a 93 cobra build with an HO cam and 19lb injectors.edit:and we have spark. Quote Selected
New motor - lost fuel pressure Reply #1 – January 03, 2008, 05:17:19 AM Put the key to the on position you should here the fuel pump come on if you don’t here it turn the car off and redo put the key to the on position again repeat till you here it or feel it. If you don’t then there’s you problem start diagnose from there. If you do here it or feel it then check the filter and get a fuel pressure regulator and see if you have pressure Matter a fact that’s all you have to do to see if you have FP. if you don’t have a FPR good luck but you can try and fell for movement in the fuel lines under the hood or disconnect one being careful w/ a rag around it and a can just turn the car to the on and off position but be very careful of your operating ignition system Quote Selected
New motor - lost fuel pressure Reply #2 – January 03, 2008, 12:00:35 PM Pump primes but we get nothing at the valve in the engine bay. I haven't checked the one at the rear of the car. Quote Selected
New motor - lost fuel pressure Reply #3 – January 03, 2008, 04:52:28 PM I have oil pressure and unplugging an injector causes fuel to spray out when the key is in the run position. Still don't have access to a fuel pressure gauge though. It almost sounds like the ecu is cutting off fuel but what would be the reason? Quote Selected
New motor - lost fuel pressure Reply #4 – January 03, 2008, 08:29:29 PM plugged filter? Quote Selected
New motor - lost fuel pressure Reply #5 – January 03, 2008, 11:14:02 PM Quote from: Seek;195621 It almost sounds like the ecu is cutting off fuel but what would be the reason?If you have F/P at the rail you have other problems... The EEC will not fire the injectors if it doesn't have power or not receiving a pulse from the TFI... Just cause you have spark doesn't mean the computer is receiving the pulse... That would be possibly a wiring issue or maybe the EEC relay took a dump... Does it have power to the injectors??? The EEC provides ground for each injector... Try a test light on a injector circuit back to the EEC(on the injector(s), what ever color other than the red), the light should blink while cranking...Even possible you have a bad ign sw... Quote Selected
New motor - lost fuel pressure Reply #6 – January 06, 2008, 01:21:47 PM One of the injectors got stuck open and was flooding the motor with fuel...that cylinder now apparently has a blown head gasket. Filling the cylinder with air causes the coolant to begin flowing. Compression on the cylinder is 120psi...which started to spew lovely antifreeze. The head's tightened down right and when we had the head off before, the entire surface was seating perfectly (yes, replaced the gasket). Before I go tearing the side of the motor down, does it sound like anything other than a bad head gasket? What a PITA, all because of a injector that got mechanically stuck open (and doubtfully from debris). Quote Selected
New motor - lost fuel pressure Reply #7 – January 07, 2008, 01:48:28 AM Is there anything else you guys can think of that I should check out while the motor's apart for the head gasket? I'm sure thats the only problem and we've changed the oil a couple times during this ordeal to keep the stuff thick. Full output of fuel into one cylinder, compressing, isn't too good on a gasket but can't think of anything else it may have affected.Either way, the engine has to be put off until next weekend - head will finish being pulled tomorrow to get any water out of the cylinder and the one next to it and reoiled up. Quote Selected
New motor - lost fuel pressure Reply #8 – January 07, 2008, 11:14:55 AM I hate to say this but it IS possable more damage could get done by "hydraulicing an engine" Quotehydraulicing: Where enough liquid gets into a cylinder at one time to provide a solid block preventing the piston from rising; causes engine damage. QuoteDetonation, pinging, gas or water hydraulicing, and overrevving your engine will cause the rods to bend. http://www.mondellotwister.com/RebuildYourFirstEngine.pdf [/SIZE][/FONT] A Bent Rod I have seen.I have heard of broken pistons. sorry but you DID ask if there was anything else. You could always reassemble and hope for the best. Quote Selected
New motor - lost fuel pressure Reply #9 – January 07, 2008, 02:32:12 PM I'm really hoping thats not the case...pulling the plugs and cranking it over didn't empty much fuel (but more than should be there) and only sprayed water mist after we had done a leakdown test where the water began to flow from the compressed air going into the cylinder. With rings not even set yet in the motor (haven't had the car together enough to drive) the cylinder gave us 120psi compression as it last tested - around the same as the other cylinders which checked in at 120-130psi.Here's to hoping that the Scat rods hold up to the starter cranking...May get lucky considering the motor itself wasn't running at the time the head gasket blew. Quote Selected
New motor - lost fuel pressure Reply #10 – January 07, 2008, 02:34:23 PM oh, how much bend would occur to a rod in the above cirspoogestances where the starter is what provided the compression? Be noticeable when hand turning the motor and looking at the piston or would we "need" to pull the oil pan? Quote Selected
New motor - lost fuel pressure Reply #11 – January 08, 2008, 02:20:51 PM Head gasket was intact but still might have slipped water by...had the head checked and its perfectly flat. There is a horizontal (not vertical up the cylinder wall) mark in the cylinder that doesn't rub off so we're trying to figure out whether or not its a crack.Water in it and an adjacent cylinder leads to me to believe the cylinder wall is fine but can't guarantee that coolant didn't drop into it from pulling the head off. The machine shop's best guesses are either just swap the head gasket and hope for the best or possibly finding a new block to machine. They don't "think" the rod would be damaged since the only power being applied to this during the time when it blew the gasket was the starter motor. Quote Selected
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