Fuel pressure test
Thread Starter
TECH Apprentice
iTrader: (1)
Joined: Mar 2011
Posts: 315
Likes: 0
From: waverly, ohio
Fuel pressure test I got my lq4 swap in my caprice to cough. It kinda ran for a couple seconds. I'm going to check the fuel pressure tomorrow. I know it supposed to run 50-55psi. Will testing it when it first primes to start give me an accurate reading?
Fuel pressure When you turn the key on the pump should run for a short period and then shut down. Cycle the key several times to prime the system and watch the pressure gauge, it should come up to operating pressure and be stable for a while. If the pressure bleeds off fast you are leaking back into the tank or injectors stuck open. If the engine has been setting for a long time the injectors may be clogged. Do a search on how to clean them. Did you have the VATS programmed out?
Thread Starter
TECH Apprentice
iTrader: (1)
Joined: Mar 2011
Posts: 315
Likes: 0
From: waverly, ohio
The VATS have been taken out. I had the ecu double checked. The 1st prime went to 20psi, the second brought it to 50psi. I have 10v at the fuel pump and I got 12v on the switch wire for the fusebox. I used the old distributor wire as my switch 12v source. If the case would be where the voltage was dropping while it cranked how would I remedy that situation?
If you're using the old distributor wire then it wont drop power when cranking, and the resistors were only on points type distributors. What car is this in? If it's the impala in your avatar, it would have had an HEI originally, and would work, however, you really only want it to control an ignition relay so you're not putting everything through your ignition switch that wasn't designed for that kind of load. You may already be seeing an effect of it by the 10v at your pump, that sounds a little low and can cause lean problems down the road if the pump isn't able to make the correct pressure because there isn't enough power going to it.
Trending Topics
You wont find a better keyed 12v source. Almost all other circuits will loose power during cranking. Do you have an ignition relay or is the whole harness running off the ignition switch?
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Andrew
Thread Starter
TECH Apprentice
iTrader: (1)
Joined: Mar 2011
Posts: 315
Likes: 0
From: waverly, ohio
I made my fuse box like lt1swap shows. I would have to look in my car and my Chilton manual because I haven't really got to know the electrical system of this car.
Thread Starter
TECH Apprentice
iTrader: (1)
Joined: Mar 2011
Posts: 315
Likes: 0
From: waverly, ohio
I found a ignition specific place on the fuse box with better results, but no luck. I wired the fuel pump directly to the battery on a toggle switch with no luck as well. Going to look into a new filter and pump.
If you're only getting 50psi with the pump wired directly to the battery, then I'd say youre on the right track, could be the pump or clogged filter. There are knock off Walbro pumps on the market that are not as good as the real thing, did you buy it from a reputable company? That being said, the engine should run on 50psi. How long has it been sitting? Could have clogged injectors.
Thread Starter
TECH Apprentice
iTrader: (1)
Joined: Mar 2011
Posts: 315
Likes: 0
From: waverly, ohio
I bought it from summit. It sat around for a while before I installed it. I thought about cleaning the injectors just to be on the safe side. I couldn't tell you how long the intake sat around because I had a msd-6010 on it before.
