Esteban Gutierrez says Haas is still seeking a solution to the fuel sensor problem which curtailed its first day of the second Barcelona test.
Gutierrez resumed testing duties for Haas on Tuesday but completed just 23 laps before the issue occurred in the morning. It followed an encouraging first week at the Circuit de Catalunya.
Speaking about the limited running, Gutierrez said: "Well, it's not ideal! There's not a lot to say. We have a solution to find, which the team is working very hard at the moment to get back on track. Let's hope that we can fit in three days what we had in four days."
Despite his frustrations at a limited day of running Gutierrez is confident the team can find solutions before he gets back in the car on Wednesday morning.
"As we said last week, you can expect to have these days where the whole programme is interrupted. We are a new group of people, on our side as a team we need to be on one side very patient and on the other side keep pushing to be efficient and make sure when we have a problem we find a solution quickly. There's not much else to say about that. I think we are confident tomorrow we can continue our programme.
"I think we will try to put in three days what we wanted to do in four. We will try to be very efficient, we have to be open for more interruptions -- that will happen and that's why I mentioned we have to be patient around it to find a solution."
Team boss Guenther Steiner says the team will look for the fix overnight after using its afternoon off to tick off another job it needed to complete before Melbourne.
"It is the first time it has cropped up and we need a bit of time to react to it but we will be out again tomorrow ... They are working on it now because we used the afternoon because the FIA is here to simulate a race weekend to go to the FIA to check the car, so we hadn't started. We analysed the problem and we could fix it with the night shift but we need to do some practicing of a whole race weekend with the FIA inspection. Now they start to fix the car."