My 94 LeSabre has a about 34 pounds of preasure in the fuel line by the engine and as soon as I step on the gas it drops down to 10 pounds. My mechanic thought it might be the diaphram above the fuel pump in the gas tank not working properly and told me to replace it with just a rubber hose. I took the tank out and this has been done alredy. Any other ideas that might be causing my problem of lacking gas line preasure to the motor?

sounds like sending unit gasket is leaking. drop the gas tank...sorry

This truck is fuel injected, the problem sounds like a weak fuelpump, it runs when you pour gas into it until that gas runs out, the first thing is to test the fuel preasure, if the pump is weak it may run with gas poured into it but wont idle, also a common problem is the coolant temp sensor and the ground wires to thermostat housing bolt but i wont bet its the pump inside the fuel tank, if you put a fuel gauge on it there should be at least 55-61 psi if its a few pounds lower it can cause problems, you have everything else and it runs with gas poured so its a fuel problem check the preasure, theres a valve up top on the fuel line to connect a fuel gauge to it, start there hope this is helpful.

When the ignition switch is ON and the fuel pump is running, the fuel pressure indicated by the fuel pressure gauge should read 379-427 kPa (55-62 psi) . The spring pressure inside the fuel pressure regulator controls the fuel pressure.

A fuel system that drops more than 34 kPa (5 psi) in 10 minutes has a leak

check for a fuel leak, some will leak along the side of the car A fuel leak. in the high pressure side also known as the feed line will cause it to crank over longer before it starts the car .. If the car is running check under the car 9 times out of 10 you will see fuel dripping from the area of the leak Its not too often you will find it if its not running...good luck

check the fuel preasure , also will it restart after it dies, if you have spark and fuel it should run, maybe not enough fuel preasure? thats only if it wont restart, good luck.

even if you have preasure in the line that does not mean you have fuel going into the engine. you should check the injectors to see if they are spraying and if not you need to check the injector pulse to find out if the PCM is sending the signal to them to spray. to check injector pulse you will need a noide light to test the pulse it the light lights up you have pulse, but easy way to check is pull an injector and turn the engine over see if it sprays.

No this is normal. As an engine wears then oil preasure will be less this is not due to a weak oil pump but wear in crank shaft bearing's. When an engine is new and bearings are tight then oil preasure wont fall a lot from reved up to idle as the engine wear's oil escapes quicker from the crank shaft bearings. Reved up oil preasure increases idle it drops off. If the oil light stays out then their is enough preasure to lubricate the engine. In fact in an older engine high oil preasure is a worse complaint as this means the oil system is clogging. All is ok with your pump. If the oil preasure is moving up and down at constant rev.'s then the oil pump is faulty. Hope this put's your mind to rest.

There is the possibility the oil sending unit might be bad, but it is more likely that the oil preasure drops to a dangerous level when the engine is warm and the oil thins out. It would be advisable to take it to a shop and have them check the oil preasure with a remote preasure guage just to be sure before it could cause major and very expensive damage.

Clogged Catalytic Converter. What happens is as you push down harder on the accelerator you force more gas into the system causing a slightly richer mixture and more exhaust flow is neccessary. The easiest way to look for a clogged cat is when it's dark out take it for a ride causing it perform it's problem look under the vehicle if the cat is literally glowing red hot you either have a clogged cat or an extremely rich fuel mixture.

its the fuel pump...........it will go completely out soon therefore your car will not start......replace it and you engine will not bog down.........you might also need a tune up.....if you havent had one in the past couple of years then you need it........