I have own two 94s and both vehicles' brake pedals would lower when the engine is started. I always assume it was the brake power booster activating and it was just the nature of the beast.
That's how it works. Totally normal.
My last 94 and this new to me 94 both also have/had a lot of brake travel when braking, but seem to stop just fine.
So this isn't normal then?
Probably not normal. If these vehicles have the sihtty 254mm (10") rear drums, they're just about guaranteed to be way out of adjustment. Adjust the rear brakes, see what happens.
Air in the ABS is also common.
Bleed the ABS module at the ports on the sides of the valve body there is tiny steel balls under the rubber dust caps use a rounded tipped punch or object to not scratch these balls or may cause a leak, depress these balls while you are pressure bleeding the system from the top,
Not applicable to the newer, "EBC310" series ABS controller. That did work with the older EBC4 controller. The "proper" way is described in the .pdf below.
also if you can get a brand new master cylinder ac delco go this right all the so called new or reman units from your box auto parts store for these style of trucks are down right garbage,
I bought an AC-Delco master cylinder for my '88. Fookin' thing was made in Communist China like all the usual auto-parts-store brands.
OTOH, it did work. But then, I have reasonable results from the normal auto-parts-store parts, too.
bench bleed the master cylinder in a vise first this takes over 100 stokes of the piston in the master cylinder bore, use the hoses connected at ports of master make sure there secured an submerged in brake fluid in reservoir an they do not slip out an slowly depress the piston 20 times slightly tapping on body of master cylinder to help aid in release of trapped air,
Yup. Many folks do not get all the air out of the master cylinder during "bench bleeding", and that air is unlikely to be released in-the-vehicle. Then they blame a "defective" master cylinder when the truth is they just didn't spend enough time and effort to properly and THOROUGHLY bench-bleed.
also I have find using the stainless steel braided flex lines at both front wheels an rear line from frame to axle helps a lot,
I'm a fan of the steel-braid-over-Teflon (PTFE) liner brake hoses. That said...even new rubber hoses are an improvement over aged or cracking original hoses. The rubber hoses swell over time, reducing the fluid channel. The brakes are relatively slow to engage...and release. This is often more-apparent at the rear, where you're feeding two wheel cylinders with one hose.
make sure your rear brake shoes are adjusted properly and that all hardware is installed correctly,
VERY important, absolutely crucial with the crappy 10" leading/trailing shoe rear drums.
the front calipers there is not much to go wrong, if there not leaking and the pistons move freely in the caliper bores you are golden here
Yes...but...it's REALLY COMMON for the caliper pistons to not move freely in the bores. In fact, it's almost epidemic where aluminum calipers are used. Even iron calipers build-up dreck, sludge, and they coat the square-cut seal with a hard "crust". The pistons get the same sort of sludge build-up on them. Anyway, the piston doesn't move freely leading to uneven braking and if it gets bad enough, poor braking and/or rapid pad wear.
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As said, the ABS MUST be properly bled, and that usually means using a scan tool to perform an "automated bleed" sequence before doing a final-bleed at the calipers and wheel cylinders.
