Whenever I push the gas pedal on my 1990 Bronco with the 5.0 302 down more than an inch or so the truck seems to lose power. It sputters and backfires and just doesn't want to go. The only way I can get it to pick up any speed is when I pump the pedal repeatedly while only barely pressing it. Everyone kept telling me I needed a new distributor cap, rotor, plugs or wires. I changed all of those and there's no change with the problem. It just keeps sputtering whenever I drive it. I could press the pedal all the way to the floor and all I get is sputtering, a few pops, a backfire or two and no power.

I know the first thing people always say is to read the codes, but I don't have access to a code reader at the moment, nor the money to buy one. I've also replaced the fuel filter with no change. So far friends have mentioned everything from leak in a vacuum hose to needing a new fuel pump. I was just hoping to get the opinions of people who actually own similar vehicles and may have experienced something similar.

If anyone has any thoughts, please let me know. In the meantime, I'll be trying to get my hands on a code reader. Any ideas on what could be wrong would be greatly appreciate though.

Thank you,

C.

 

Ford Fuel Injection has instructions for pulling codes using a paper clip. also some autoparts stores will pull codes for free as well. this is a great feature to have so your not chasing ghosts.

also have the fuel pressure checked at the rail. you might also have a clogged cat converter, if you unbolt the y pipe from the exhaust manifolds and drive it for a short distance you should notice a big change if not then that isnt the problem.

pull codes first is so important so dont skip this.
how many miles are on the motor? checking the timing would be good as well.

 

I have a similar problem.
1990 5.0L FI 124000mi Auto No Check Engine Light, No Codes.
I just rebuilt the Distributor with new everything. Timing was set.
Engine runs and accelerates great when it's not under a load, i.e. neutral or park
The engine seems to be lacking fuel when under load. The smell of gas is noticeable.
Engine runs rough and sometimes dies when stopped at the light.

 

Well, I used the "paper clip method" to read some codes earlier and these are the two that I got. I'm not exactly mechanically inclined, to say the least, so any advice on checking on these further would be appreciated.

Code 33: EGR valve opening not detected.

Code 87: Fuel pump primary circuit failure. When the FP relay was activated by the EEC, voltage was not detected on the control circuit.

 

Code 33... well since the EGR valve needs to open and the computer isn't getting that information either the EGR valve has failed and isn't opening, the vacuum line running to it is broken and not giving it the vacuum it needs to open, or the electronic connection to the EVP (Egr Valve Position) sensor is damaged or broken. This sensor "tells' the computer the position of the EGR valve). There are other possibilities but these three are the most likely.

Code 87... this is a more critical issue but would keep the engine from running at all if the circuit that powers the fuel pump truly is dead. This is most likely an intermittent problem that should be looked into at the wiring harness or the ground for the pump.

 

I'm in the process of trying to check all of these things out. Truthfully, I've no idea what I'm doing bu I'm trying to learn as I go.

However, a new problem has developed. I tried to put new spark plug wires on again but there was no change so I went back to the old ones, which were still relatively new. During the process, I also removed the air filter to check it, and it was pretty bad. However, I tried to drive it around the block and.. oops.. forgot to put the air filter back in. I did so as soon as I realized it and I'm going to replace it today anyway.. but now whenever I get the truck up to about 15 mph or so the entore engine starts to shake like mad. Not vibrate, but shake. It shakes a bit even when just idling in park, but it's horrible when I'm driving. This is something new I've never had before, so I must have done something wrong. Any thoughts?

I really appreciate all the help. Thanks.

 

You still havent mentioned the mileage of the engine. There are a number of things that can cause problems in the truck, first correct the ones that come up before moving to others. I would check to make sure you have a good ground everywhere there is a ground on the truck. If the grounds are dangling, then someone didnt put a ground back on or a ground corroded in two. These trucks are very dependant on the electrical system running properly with out issue. Also because of the fuel issue, change the fuel filter if you have yet to do so, and get the fuel pressure checked at the fuel rail. Been down the road and it is a painful but rewarding trip in my opinion.

 

sound to me like you got a few plug wires on the wrong spark plug. if you have 7 on 8 and vise versa it will cause the engine to shake just like you mentioned. ive done it

 

Yep, the #7-to-#8 swap had me all worried that I'd messed up something serious first time I replaced wires.

 

Check Firing order - 1-3-7-2-6-5-4-8
4 8
3 7
2 6
1 5
0