new stroker, no power, fuel pump?

redrider2911

redrider2911

NAXJA Forum User
Location
Yakima, WA
So I just go my stroker all fired up this last week but I'm having an issue and didnt have any leads on the possible problem until today.

This is what I've built

87 renix block bored .40 over
258 crank and rods
68-232-4 comp cam w/ lifters
87 renix head w/ 3 angle valve job and some porting to adapt 99 intake
99 intake w/ blue top 460 injectors
94 TB bored 60mm strait through with renix adapted tps
94 fuel rail and fuel lines.
90 Renix exhaust (no money to upgrade yet.)

Did I leave anything out?
Anyways, this thing has great low end torque off the line already. For the couple seconds it lasts... If i hit it at WOT some times it hesitates and some times it doesnt. Even though it hesitates it jumps off the line but then starts to cut out and fall on its face around 2200 rpms. I cant even get up to freeway speed but in 3rd it seems to hold well at 21-2200 rpms if i push the gas down any more its like it chokes out. Because it seemed like there was a sweet spot in the throttle I thought it was the tps which still needs fine tuning (output voltage sitting at about .72) I got ahold of a friends pressure gauge today and checked the fuel rail, while the engine is started there is no fuel overflowing into the return line and the pressure reads about 25. I replaced the filter and still the same problem ( this jeep had been sitting for two years.) The fuel pump doesnt wine but it doesnt retain pressure in the rail when the key is off. Could this be my problem all along?

Sorry about the long description but i guess the more details the better.
thanks in advanced.
 
Check your distributor indexing.
 
The jeep sat for two years half full of gas so i hot wired the fuel pump to empty it out then put shell premium in it plus some lucas. One of my friends suggested that maybe the screen on the end of the pump is all clogged up. Whats strange is the pump sounds healthy. I knew the numbers were 31 and 39 without vacuum, the guy that let me use the gauge told me it wasnt too far off to cause and problems. :twak: Just wanted to make sure i didnt need to run a bigger volume pump for the injectors even though they are rated for the same psi...

As far as the distributor, advanced it one tooth and it wouldnt even start, retarted it one tooth and it ran like crap. It started missing like crazy w/ any gas on it, all though it did sound pretty good at an idle. My jeep has recently started doing the whole high idle thing every now and then but i think its just the stepper motor.
 
25 psi is quite a ways off from 31/39 PSI. I would start with the fuel pump to get the pressure up to where it should be then see what happens. What is the info on your injectors?
 
I pulled them out of a ford f250 with a 460 from the junk yard. Blue top injectors, I never pulled a part number off of them. I cleaned them the best i could using sea foam then like i said I ran lucas in my first tank.
 
From what I could find the injectors flow 24lbs @ 45 psi. So on your fuel system they would flow 20 lbs @ 31psi and 22 lbs @ 39psi. However at 25psi they would flow 17.8lbs. I would really need the injector part number to verify though. Also, depending how the injectors were stored and how long they sat with gas in them they could be clogged.
 
You are correct but i figure at 39psi they should flow atleast 21 right. k so i took out the pump and it must've been replaced before because the hose inside the tank was barely holding on to the pump nipple. drove it and it ran amazing for about ten miles then it started to sputter and no power. this was different and it happened on my other jeep before too. for some reason it seems i have trouble seating the pumps in the tank correctly. I've repositioned it 3 times and im still getting the loud whine that wasn't there before. is there a trick to this?
 
Sure... what would you like pics of? i can physically get the pump in and it feels like it seats and even twist the lock ring on. it runs great for awhile until the fuel pressure drops again. is it really that important that it seats in there? what does it sit in and why.
 
Said the hose on the outlet of the pump was loose or came off? Did you put a good hose clamp on it? Seating the pump doesnt have anything to do with it, just sits in the baffle, and the tang on the sender lines up with the notch in the tank. What was the fuel pressure when it was running 'good'?
 
Yea i reclamped the hose on there. i didnt have means of testing pressure when it was running good but it retained pressure at the rail when off and unlike before it was pumping enough pressure through the fuel rail to push the regulator open and a good amount of fuel into the Return line. now that its running bad again there's barely any flow to the return line at idle. could the pump just have been on its last leg before it decided to start whining?
 
I would replace the pump and pick up a fuel pressure gauge. The gauge isn't expensive.

The only way to know if the injectors are suitable is by using a wide band O2 meter. 21lb might not be too bad. I know other people use Mustang 24lb injectors, but I don't know the true flow rates of them. You can't compare what the HO flows vs what a Renix flows for their injectors. The Renix may just holds the injector open longer vs the HO.
 
I figure with all the sensor and the knock sensor the ecu should adjust the pulse width as needed. Im going to do a map sensor adjuster too but havent had the time, it doesnt sound like im running lean. So I disconnected the hose from the fuel rail and before the fuel filter, blew it out with my mouth, then reconnected it. It ran great again for a while then started to hickup from lack of fuel. I replaced the fuel filter again for the second time and its running much better now but i can tell its gradually getting worse. I'm running shell v power gas and lucas, is it possible its really clogging up the filter that quick? Also noticed my torque converter slipping a little bit. I was a little low on fluid but curious if any of you guys upgrade your torque converter?
 
It can clog the filter if you have crap in the tank. But I'm betting the pump is reducing pressure as it runs. Did you check your fuel pressure when it is running good and when it is running poorly?

I have heard of two people that upgraded the torque converter. I don't think it is necessary. Also, it will make the transmission run hotter.
 
It is possible the pump is week, but on both of the pumps i tried?... Since im going to buy a new one, is it possible to find a aftermarket with a higher volume rate or possibly put in a newer xj pump with the regualtor built in to accomodate the injectors better?
 
You don't need a higher pressure/flow pump with the injectors. Also, the later pump with the regulator on the pump will create a few problems for you.. namely you would need the tank to go with the pump, and the fuel rail along with eliminating the return line. Its also more expensive to adjust the pressure on that style pump than your with the FPR on the rail.
 
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