chris1 Posted July 19, 2015 Report Share Posted July 19, 2015 I just replaced the head on my 87 starion, added Ajusa gasket and ARP's, and rebuilt the TB. I eliminated basically everything except PS. It has a 14g turbo with no shaft play. It runs well and spools nicely for the first 10 minutes or so and then falls on its face when the turbo begins to spool. If I shut the engine off until my boost gauge returns to zero, I can restart the car and it will run fine again for several minutes. I have also noticed the fuel pump becoming gradually louder until it begins to run poorly again. I have a new filter, replaced the fuel pump, and removed the pick up screen and added an in-line filter before the pump. It also has a rough, sputtering kind of idle that smooths out completely for the few seconds it will run without the MAF plugged in. Could my MAF be the issue?Could you guys give me some ideas of what to look for? Thanks Link to comment Share on other sites More sharing options...
pcristquester Posted July 19, 2015 Report Share Posted July 19, 2015 Did you leave the small cone filter in? It may be the issue Link to comment Share on other sites More sharing options...
pcristquester Posted July 19, 2015 Report Share Posted July 19, 2015 Or the inline filter you added is restricting fuel volume. Since you know the fuel pump is consistently acting up, I bet your problem is in that area. Link to comment Share on other sites More sharing options...
PSiTSi Posted July 19, 2015 Report Share Posted July 19, 2015 check for boost leaks. Link to comment Share on other sites More sharing options...
ucw458 Posted July 19, 2015 Report Share Posted July 19, 2015 I vote inline pre-filter. They aren't necessary and if you install one that's too small it causes problems. Most cheap pre-filters are junk. Needs to be no finer than 100 micron and must have lots of surface area. If the filter is too small or too fine it restricts flow and causes cavitation in the pump. Cavitation destroys pumps and reduces fuel flow. I don't run a pre-filter in mine. Just the in tank screen. Link to comment Share on other sites More sharing options...
chris1 Posted July 20, 2015 Author Report Share Posted July 20, 2015 The problem originated prior to installing the pre-filter. I only installed it after removing the screen at the bottom of the pickup tube as it had disintegrated. There are no cone filters in line before the pump. I checked the gas cap to make sure excessive vacuum wasn't building in the tank too. Link to comment Share on other sites More sharing options...
StarquestRescue Posted July 20, 2015 Report Share Posted July 20, 2015 Buy the correct filter for the pick up tube and ditch the bs inline one. Link to comment Share on other sites More sharing options...
ucw458 Posted July 20, 2015 Report Share Posted July 20, 2015 Your mass air sensor may be an issue. Only some 86 cars could run without the mass. Regardless of what your issue is the pre-filter could be an issue. Also check the voltage going to the pump. If it's below 12v you could have pump issues. You can eliminate that black box before the pump connections. It's just a resistor. Running a new power wire from the battery for the pump is the best thing to do. 1 Link to comment Share on other sites More sharing options...
importwarrior Posted July 20, 2015 Report Share Posted July 20, 2015 get a new screen from the dealer or Enginemachineservice.com AKA --- DAD on here. http://www.enginemachineservice.com/ems/parts/conquest/fuelsystem.php Link to comment Share on other sites More sharing options...
81zfan Posted July 20, 2015 Report Share Posted July 20, 2015 Engine Machine is where I would shop and get things if he has them in stock. Randy is cool to work with and help ya out when you call him to order. I always try to keep the money flowing on here instead of the dealer...We need it more than they do Link to comment Share on other sites More sharing options...
speedyquest Posted July 20, 2015 Report Share Posted July 20, 2015 This comment ---> "If I shut the engine off until my boost gauge returns to zero, I can restart the car and it will run fine again for several minutes" I'm really confused by that. What do you mean exactly? Your car doesn't build boost at idle... so why would you need to shut off the car to get your boost gauge to 0psi? Link to comment Share on other sites More sharing options...
chris1 Posted July 20, 2015 Author Report Share Posted July 20, 2015 I'm sorry. What I meant was that I leave my ignition off long enough for the needle on my aftermarket boost gauge to return to zero from vacuum. I've also noticed that my fuel pump becomes quiet again after that. I removed the pre-pump filter but it didn't improve the problem. I also get my parts from engine machine service. They've always been excellent to work with.I checked my fuel return line, it is clear.12.4 volts at pump, removed the resistor.I guess I need to hook up a fuel pressure gauge and see what happens while I drive. Link to comment Share on other sites More sharing options...
ucw458 Posted July 20, 2015 Report Share Posted July 20, 2015 Could be the pump overheating. When it gets loud does it get hot? You could try packing a bag of ice around the pump to see if it slows down the problem. If it does you may have a defective pump. Fuel pressure under load is a good thing to check. Link to comment Share on other sites More sharing options...
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