Fuel Pump

ALange · September 2, 2009

My 454 has bone crushing torque pulling a load up to 55MPH. After that I have trouble pulling an empty 20 foot box trailer. It is a 5spd standard with 410 gears in tip top shape and very lows miles. It was suggested to me by a member here that my fuel pump may not be holding pressure adequately as the RPMs go up. It does start whimping out after about 2800 RPMs when it has a load in tow. Here is the question. To buy the tool to test pressure, or to have a shop perform the test would cost more than if I just bought a new pump and a six pack of beer and swap ouit the 15 year old pump. Can I install a higher output pump than factory stock without hurting anything? The reason I ask is I may be modifying the engine if I cannot get blood from a stone and I would use the new Edelbrock port injected manifold system that requires higher pressure. I don't want to replace the pump twice. BTW, I have a chip in it, flowmaster, K&N and it has been dyno'd and the shop says the engine is running fine.

2COR517 · September 2, 2009

Personally, I would be surprised if the pump is the problem. However, I would buy the gauge at Autozone or whereever, and check it out. I think the TBIs run at about 12-15psi. Ideally you can set it up so you can see the gauge while you drive. Once you rule out the pump, (and the probably the fuel filter) I would be looking to the ignition and doing a full tuneup/induction system cleanup. Start by pulling the Throttle Body. You can get a gasket kit at Napa. The TB to intake gaskets are notorious for deforming/cracking and leaking. Once the TB is off, pull the Idle Air Control. You might want to get an IAC gasket at the dealer. Mine cracked when I took it off. I have some form a gasket on the threads. It works for now, but I need to grab a gasket. Remove the Throttle Position Sensor. Pull the top half of the TB apart. Now you can really start cleaning the TB without worrying about damaging any of the sensitive components. Get at least a couple cans of throttle body cleaner, and an old toothbrush and just go to town. Clean all the ports, and the IAC valve. The TB should be spotless when you are done. Put everything back together and start it up to make sure the truck still runs OK. Get the engine back up to temp. Now it's time for the magical Seafoam. When the engine is hot, pull the brake booster vacuum line, and suck in a can of seafoam. If your truck has hydraboost brakes, you can use any manifold vacuum line, or just pour it into the throttle body. Split it between each side. I use a funnel. Pour it in just fast enough to not stall the engine. As soon as it's in there, shut the engine down. Put the other can in the tank. Pull the two (usually two anyway) ECM fuses under the hood to let any codes clear. Let the Seafoam work for like an hour. While it's sitting, change the fuel filter and air filter. Change the O2 sensor too. There like $60 at Napa. They can get lazy with age and affect power and economy without throwing a trouble code. After the hour or so is up, put the ECM fuses back in and start the engine. You should have a huge cloud of black smoke pouring out of the tailpipe. Take it for a drive, and really open it up a few times. After a few minutes the smoke should stop. You will probably notice some big differences in the truck just from doing this. Finally, ignition. ACDelco Cap & Rotor. ACD plugs. Plain boring plugs, gap them about .035. You don't even need platinum, but get ACD whatever you do. Get your plug wires from NAPA. Get the premium wires, Blue Max by Belden I believe they are called. When replacing the wires, clean the tower on the coil nice and shiny. They are notorious for corroding. If the mileage is up there on your truck, you might want to consider putting in a reman distributor. You get a new pickup coil and ignition module. These are also trouble some times, and worn distributor bushings can contribute to pickup coil problems. I am replacing the distributor on my Tahoe tonight. When I did these steps to my trucks, they felt like brand new machines.

One more tip. To help get the O2 sensor out, go to your John Deere dealer and get a can of Fluid Film. This stuff is a fantastic penetrant. It works slowly, but it's great stuff. Spray the O2 sensor down everynight for a few days. Use a 7/8 SIX point box end wrench to pull the sensor. Sears carries that wrench. You will have to cut the plug off the sensor to get the wrench on.

Good luck, keep us posted.

HawkScot · September 2, 2009

Had a 92 Burb that ran fine, up to a point, then just did not have power. I did a bunch of things, but in the end, it was fuel filter. change the filter.

ALange · September 3, 2009

The fuel system has a new filter and I did have the TBI flushed and cleaned by the shop that did the dyno. I has a MSD dist and I have checked cap and wires, also new. I guess I'll just replace the O2 and the pump for now. Age alone is incentive enough. Thx.