98.5 no start without either.

C

cwente

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Aug 1, 2010
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ok as the title says. i rebuilt my motor a month ago and have to start with either ever since. i have no tach and a check engine light. its not losing fuel through the return. got 16psi from brand new fass. no air leaks. only thing i can think of is its got a cam sensor from an 02 but i dont know if it makes a difference. brand new crank sensor. it runs great once its running. any ideas?
 
How long does the fass prime before you start your truck? I had a problem with my truck starting after I installed my airdog. If the lp runs for more than just a second or two when you turn the key, you might try wiring in a delay switch. Start the truck with the lp off and then turn it on with the switch. Mine runs great now. Seems the vp doesn't like too much fuel pressure to start...
 
Is it your original IP? The older ones had a thinner internal diaphragm that will rupture with the addition of a upgraded lift pump. Later ones had a thicker one. The way I was taught is that its the internal pressure regulator and with the new found pressure of a better LP the rubber is not used to the pressure and ruptures. Longer and longer starts turns into no starts w/o ether. A fix is to plumb a hobbs switch on the oil filter mount so the LP doesn't fire till after the engine does. The easy method to check is disconnect the LP relay and see if it fires instantly. This is the only reason I replaced my IP, eventually only ether would start it. Always ran perfect once started though.
 
thanks nrose07 and Hill Billy. but it wont start without either with or without the pump on.i had a total of 7 trouble codes 2 were my apps but i replaced that but knew that wasnt this problem. a few were my crank sensor voltage being low it said. but i know thats the reason the tach wont work. would the crank sensor not picking up cause the engine for whatever reason not to realize its running til it fires on either? im not sure if it even makes sense to be that but just an idea
 
During the rebuild were all the same parts reused. Your absence of a tach signal is your whole problem for sure. I've fought several of them with the same issue. Your crank is the same and geartrain is all original?
 
Well let me retract that statement. The "for sure" part was pretty ignorant. But it's definately an issue. Sorry about that
 
yes all 98 parts inside. only 02 parts are the block and head. its got the crank sensor but its just like its not reading it. could it be a computer issue not sending a signal or something?
 
So you are using an 02 block, are you attempting to read your RPM through the Cam Sensor or the Crank Sensor? Being a a 98,5 and you should the wiring harness for both the Cam and Crank Sensors. What year is the ECM, your 98.5?
 
yes 02 block. it has the hole by the starter the 02 wiring doesnt use. i put a crank sensor in it, have the 98 crank with tone ring, but tach doesnt work. have a code for low voltage to crank sensor. im thinking its the pcm doing that. does that sound like it could be the issue?
 
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