KiMifan Posted July 22, 2010 Share Posted July 22, 2010 Unless the shop has one of those "No returns on electrical parts" signs behind the counter! I'm still leaning toward a charging problem or the battery itself. Quote Link to comment Share on other sites More sharing options...
TurboShortBus Posted July 22, 2010 Share Posted July 22, 2010 Unless the shop has one of those "No returns on electrical parts" signs behind the counter! I'm still leaning toward a charging problem or the battery itself. Yeah, the dealership will bone you on that one, but places like Advance Auto Parts, AutoZone, etc. don't really care. At the worst, you tell them that the new part is also defective if they balk at the return. Mark Quote Link to comment Share on other sites More sharing options...
Trevor571548534737 Posted July 22, 2010 Author Share Posted July 22, 2010 I checked voltage with the car running and it was normal. Holding the revs at about 3k it was like 14 volts. When the battery was tested it was "ok, low charge." So maybe it is time for a new battery. I will check fuel pressure today. Quote Link to comment Share on other sites More sharing options...
rocky Posted July 22, 2010 Share Posted July 22, 2010 What is the voltage at idle? Where did you get the battery tested at? If it was a parts store don't trust it. Go to a shop and have it retested same with the alt. You really need the alt tested with a VAT to see if diodes have failed. If it is generating a AC voltage it is hard to see without the VAT. I wish I could swing by and help. Quote Link to comment Share on other sites More sharing options...
Trevor571548534737 Posted July 22, 2010 Author Share Posted July 22, 2010 Ok. The battery just sitting in the car is 12.0 and idle is moving around between 13.0-13.5. holding the revs at about 3k the voltage is 15.8?! so maybe my meter is messed up? Also the fuel rail I have on the car now is a replacement I bought off a local guy, and is got no schrader valve. (wtf?) So I guess I am going to have to rig something up to test fuell pressure. Quote Link to comment Share on other sites More sharing options...
TurboShortBus Posted July 22, 2010 Share Posted July 22, 2010 IIRC, the Fox Schrader valves were down on the hard fuel rail piece that comes up from the framerail, in the area of cylinder 1. It's a piece that is separate from the manifold-mounted fuel rail. It's been a long time since I worked on a 5.0L, though, so my memory could be fubar. Mark Quote Link to comment Share on other sites More sharing options...
rocky Posted July 22, 2010 Share Posted July 22, 2010 ALT is no good it should be 13.5-14.5 volts regardless of rpm Quote Link to comment Share on other sites More sharing options...
nape1548534725 Posted July 22, 2010 Share Posted July 22, 2010 ALT is no good it should be 13.5-14.5 volts regardless of rpm Agreed. Rectifier is bad if it can't hold a voltage in that range. Quote Link to comment Share on other sites More sharing options...
Trevor571548534737 Posted July 23, 2010 Author Share Posted July 23, 2010 Just one other thing. If I am setting timing the car seems to not want to idle at the normal 12 degrees but does fine if it's retarded. Is that normal? Quote Link to comment Share on other sites More sharing options...
TurboShortBus Posted July 23, 2010 Share Posted July 23, 2010 Do you still have an old, stock or stock-style balancer? The outer ring on those can wander over time and throw off your timing settings (or, they can fool you into thinking the timing is correct when it is not). Dumb question, but you do have the SPOUT plug removed when setting the timing, right? Mark Quote Link to comment Share on other sites More sharing options...
Trevor571548534737 Posted July 23, 2010 Author Share Posted July 23, 2010 yes spout is out. I have checked timing a few times. The balancer along with most of the bolt on stuff has less than 10 hours on it. Quote Link to comment Share on other sites More sharing options...
TurboShortBus Posted July 23, 2010 Share Posted July 23, 2010 It should idle fine when setting the base anywhere between 8* and 16* BTDC. Does the idle clean up when you put the SPOUT back in after setting the base timing? Mark Quote Link to comment Share on other sites More sharing options...
Adam Ginsberg Posted July 23, 2010 Share Posted July 23, 2010 IIRC, the Fox Schrader valves were down on the hard fuel rail piece that comes up from the framerail, in the area of cylinder 1. It's a piece that is separate from the manifold-mounted fuel rail. It's been a long time since I worked on a 5.0L, though, so my memory could be fubar. Early SEFI Foxes, 86-88 had the Schrader valve on the line from the frame rail up to the engine fuel rail (on the passenger side). Later SEFI Foxes, from ~89-93 had the Schrader on the engine fuel rail, right next to the FPR. Quote Link to comment Share on other sites More sharing options...
Trevor571548534737 Posted July 23, 2010 Author Share Posted July 23, 2010 It seems like the misfire is cylinder specific, and since I have no way to really test fuel pressure without building some sort of wierd device I am going to replace the injectors. I have spark, timing, and compression. Quote Link to comment Share on other sites More sharing options...
TurboShortBus Posted July 23, 2010 Share Posted July 23, 2010 Most aftermarket, billet aluminum, adjustable fuel pressure regulators have a 1/8 NPT port on the side of them that can be used to feed a fuel pressure gauge. They can be bought for $70-$125 through Summit, but could be cheaper if you shop around. Mark Quote Link to comment Share on other sites More sharing options...
Trevor571548534737 Posted July 23, 2010 Author Share Posted July 23, 2010 I have a bbk one laying around. I will throw it on there and see about hooking up a gauge. Thanks. Quote Link to comment Share on other sites More sharing options...
TurboShortBus Posted July 23, 2010 Share Posted July 23, 2010 Freebie! Nice. You won't need anything fancier than one of those ~$25 1.5" gauges that most speed shops sell (unless you have one of those sitting next to the BBK regulator as well). Maybe throw in another buck or so for a 90* brass fitting at Home Cheapo, unless you want a braided steel line so you can tape the gauge to the windshield while you're driving it. You could also make your own line from EFI-rated hose and some clamp fittings from the parts store as a temporary fix. Mark Quote Link to comment Share on other sites More sharing options...
CMC#11 Posted July 23, 2010 Share Posted July 23, 2010 It seems like the misfire is cylinder specific, and since I have no way to really test fuel pressure without building some sort of wierd device I am going to replace the injectors. I have spark, timing, and compression. How do the plugs look? Any one cylinder with different color than the rest? Quote Link to comment Share on other sites More sharing options...
Trevor571548534737 Posted July 23, 2010 Author Share Posted July 23, 2010 Plugs are good. We checked those when we were still at the track last sunday. Quote Link to comment Share on other sites More sharing options...
KiMifan Posted July 23, 2010 Share Posted July 23, 2010 You have to check the fuel pressure under load. Idle PSI won't tell you enough to diagnose a bad fuel pump. In my years of running 5.0L Mustangs, I've had three instances of similar misfiring/loss of power/poor running. The first thing most people check is the TFI, then the coil and other related ignition parts and sensors; personally I've yet to have any of them be the cause. I chased a lot of things in each instance, but in the end, the causes were low voltage from a faulty alternator, bad fuel pump, and a bent intake valve. Quote Link to comment Share on other sites More sharing options...
Trevor571548534737 Posted July 24, 2010 Author Share Posted July 24, 2010 Anybody have a good resource about doing a carb conversion? Quote Link to comment Share on other sites More sharing options...
TurboShortBus Posted July 24, 2010 Share Posted July 24, 2010 Ugh...don't give up now! Chances are very good that it's going to be something relatively simple and/or stupid, and you'll be back up and running for a fraction of the cost of making that drastic of a change. Mark Quote Link to comment Share on other sites More sharing options...
KiMifan Posted July 24, 2010 Share Posted July 24, 2010 Don't put a carb on it. Huge disadvantage in CMC. Quote Link to comment Share on other sites More sharing options...
Trevor571548534737 Posted July 24, 2010 Author Share Posted July 24, 2010 Last night I replaced the fuel injectors on the side that was having the misfire. Now the car wont start at all. Quote Link to comment Share on other sites More sharing options...
TurboShortBus Posted July 24, 2010 Share Posted July 24, 2010 Backtrack and check your work for a disconnected harness, ground, etc. Verify fuel pressure, verify spark. What does "won't start" mean? Does it crank but won't fire, or won't it crank in the first place? Mark Quote Link to comment Share on other sites More sharing options...
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