Chevy 350 problem

I have a 88 chevy 2500 2 wheel drive with a 350 in it. Recently put a fuel pump on it but for some reason when driving it when the brakes are applied it dies, but it will start right back up. I wasnt sure if it has something to do with the brake booster or a vaccum line. Has anybody ever experienced this or know what the problem would be.

Im gonna be a smartazz and say the problem is the bowtie on the grille! But i think your on the right track with a vacuum leak somewheres in the booster for the brakes.. Bob

TEMPORARILY tug the vacuum line out of the grommet in the brake booster, cap it, and see it the problem goes away.

If so, you need to replace the vacuum brake booster unit.

lol hey now dont go knockin the bowtie can't say anything bad about this truck it has been a good truck, GM on the other hand you can knock them for screwing people on the price of a new truck lol ya im thinkin it has to be somethin with vacuum but just dont know where to really start checkin

WELL you wanted it to stop didn't you lol, if you find out it's not a vacum leak then take a look above the brake pedal might bee a bad wire up in there.

1988 fuel pump? I think this is a electric pump by gas tank, right side? You have a single point throttle body injector system working at about 30 pounds? Or is this a multiport injector working at 50+ pounds? I don"t think you would have a engine pump anymore. Whatever, check wiring by back brake lights and running next to fuel pump wires- might be a bit of rubbing and cross conecting, brakelight shorting fuel pump wire when applied. Did you have fuel pump installed at a shop or do it yourself? RN

1988 2500 have the fuel pump on the engine feeding a carb.

Nope.It's a throttle body injected truck.

I'm with Bob.Block off the brake booster vacuum hose and see if it goes away.

"I think this is a electric pump by gas tank, right side? You have a single point throttle body injector system working at about 30 pounds?"

OEM setup would be fuel pump IN the tank, TBI unit running about 9 - 11 psi.

if i was to guess it would be the torqueconverter not unlocking , kind of like braking and not stepping on the clutch on a manual trans

when you shut off the key it resets the ecm and unlocks it, you might do some research, "i think" the brake light switch also has something to do with the torqueconverter unlock, you should be able to find a wire scematic online

Alright is it an electric fuel pump in the tank or is it a mechanical fuel pump on the engine? If it is a New electric pump in the tank,it kind of sounds like its not pumping enough pressure.Did you put a new screen on the pickup tube? Also did you change the fuel filter that's up in the frame rail??

my 88 chevy 2500 4x4 isn't throttle body never was. must of switch in the middle of the year or some dang thing

switch in midyear? Maybe, thats why I asked. 1980s was transition for a lot of things-1985 was most going to fuel injection but trucks were 2 years behind EPA car rules so hard to remember what vehicles had unless someone looks under hood and posts. RN.

Could be a ground problem back under the bed. I don't know about the 3/4 ton but a friend had a half ton doing that and we found that the pump in the tank was grounding through the brake lighting circuit. This was a pump in the tank which he had changed already.
Frank

My 87 with 350 is throttle body injected with elec pump in tank.
Willie

Very possibly you have a bad pickup coil in the distributor. A very similar thing started happening with my '88: It would quit when I was cruising down the freeway at 70. One of the leads to the coil was broken, and would intermittently break connection at inconvenient times.

not a 2500 is it.

I had an 87 3/4 ton with throttle body and electric pump in the tank.

Nope, 20 series. Chevy switched from 2 digit, 10,20,30, etc to 4 digit 1500,2500, etc in 88.
Willie

Seriously doubt it is a vacuum leak. When sensor detects excess air, it signals injectors to add more fuel to correct the mixture. Excess air with more fuel to correct the mixture will kick the idle speed way up. BTDT, bad hose to heater control.
Did the problem start after replacing the pump?Time to sit back, have a beverage, & retrace the steps when replacing the pump. Did you drop the tank or lift the box? Some say it is easier to lift the box,less work & can work on pump standing up rather than lying on your back wrestling with the tank.
Did a wire to turn signal/brake lite get pinched putting things back together? If it did, it could pull voltage down enough to stop pump or ignition, but not quite enough to pop a fuse. Turn signal & brake lite use same wire/bulb, but when using signal, voltage could recover enough to keep running when signal blinks.
Weird things sometimes creep up on you, & not where you think it could be. Eg: IHC truck, 345 V8 gas, radio cut out every time I shifted. Finally got to where engine died. Start right up again, but die when tried to move. Seemed clutch pedal related, but everything ok moving clutch but not in gear, clutch linkage not touching any wires.
Problem- left motor mount bad, torque twisted motor to right, battery cable shorting to frame enough to kill ignition, then drop back, release the short & not burn up battery.
Temporary repair- wrap a leather glove around batt cable, drive to shop.
Permanent repair- replace motor mounts & add safety cable. Cable like GM did for jambed throttles back in the 70s.
Might not be your problem, but another angle to check.
HTH
Willie

Yeah I screw up big time last night, got to thinking bout it and mine is 30 series 1 ton sorry bout the mix up.